How Long to Prepare for a Coding Interview From Scratch
Stop asking 'how long' and start planning. Realistic, battle-tested timelines for beginners, CS grads, and rusty seniors.
"How long will this take?" It is the anxiety-inducing question that haunts every software engineer staring at a blank LeetCode editor. The honest answer is not "two weeks" or "six months"—it depends entirely on your starting point.
This is not a motivational speech telling you that you can hack the system in a weekend. If you are starting from scratch, that is a lie. What follows are realistic, battle-tested timelines based on hundreds of hours of curriculum design and student data.
Before diving into the details, visualize how skill builds over time. The animation below shows how consistent practice compounds—and why early weeks feel painfully slow while later weeks accelerate dramatically. Step through it to see the difference between a rushed 4-week sprint and a sustainable 6-month build.
The Variables That Matter
Your preparation timeline depends on three critical factors. Be honest with yourself here—overestimating your proficiency is the fastest way to burnout.
Starting Point Assessment
1. Prior DSA Knowledge
Do you know strictly how to use a Hash Map, or do you understand why it offers O(1) access? Can you explain recursion without drawing a stack frame? If you need a refresher on the basics, check out the best order to learn data structures.
2. Programming Proficiency
Are you fighting the syntax or the logic? If you are still looking up how to declare a map in Java or Python, add 2-3 weeks to your timeline just for language fluency.
3. Target Company Tier
FAANG companies (Google, Meta, etc.) require deep proficiency in dynamic programming and graphs. Mid-tier companies often stick to arrays, strings, and hash maps.
Realistic Timelines by Starting Point
Complete Beginner (Never Studied DSA)
Timeline: 4-6 months with consistent study (2-3 hours daily)
You need to build two layers of knowledge simultaneously: the raw tools (data structures) and the blueprints (algorithms). This takes time to bake into your long-term memory.
The "Zero to Hero" Schedule
Foundations & Basic Patterns
Focus on Arrays and Strings. Master the "Two Pointers" and "Sliding Window" patterns. Do not touch a Graph or Tree yet. Build confidence with easy problems.
Linear Data Structures
Hash Maps, Linked Lists, Stacks, and Queues. This is where most interviews happen. Start using spaced repetition to ensure you don't forget Month 1.
Tree & Recursion
The hardest hump. Master recursion visualization. Trees are just fancy graphs, but start here. Solve 20+ Tree problems to map the recursive patterns to your brain.
Advanced Data Structures
Heaps (Priority Queues), Tries, and basic Graph traversals (BFS/DFS). If you are aiming for mid-tier, you can stop here and just review.
The "Hard" Stuff
Dynamic Programming and advanced Graph algorithms (Dijkstra, Union Find). Don't memorize solutions; learn the decision framework.
Mock & Review
Stop learning new things. Focus on speed, communication, and clear coding. Read how to recognize patterns under pressure.
Some DSA Background (CS Degree/Bootcamp)
Timeline: 2-3 months with consistent study (1.5-2 hours daily)
You know what a Binary Search Tree is, but you have never implemented one to solve a range sum problem under 45 minutes of pressure. Your goal is Pattern Recognition. You need to shift from "knowing definitions" to "seeing solutions." The knowledge is there; it just needs to be sharpened and made retrievable on demand.
The "Sharpen the Saw" Schedule (8-12 Weeks)
Core Pattern Review
Rapidly review Two Pointers, Sliding Window, and Hash Map patterns. You likely learned these but never drilled them for speed. Do 5+ medium problems per pattern until you can recognize the signal within the first minute of reading a problem.
Trees and Recursion Deep Dive
This is where most CS grads are weakest. You understand recursion conceptually, but can you build a solution for "Lowest Common Ancestor" without Google? Focus on DFS, BFS, and recursive tree traversal until it becomes automatic.
Graphs and BFS/DFS Application
Apply your tree traversal skills to graphs. Tackle "Number of Islands," "Clone Graph," and cycle detection problems. The skills transfer directly once you see graphs as "trees with extra edges."
Dynamic Programming Foundations
Focus on 1D DP (Climbing Stairs, House Robber) and 2D DP (Unique Paths, Edit Distance). Learn to recognize "overlapping subproblems" and draw the state transition diagram before writing code.
Mock Interviews and Speed Drills
Stop learning new concepts. Randomize problem selection across all patterns and time yourself. Do at least 3 mock interviews with a peer or a platform. Practice talking through your thought process out loud—this is where most people fail, not the coding itself.
The hidden advantage for this group is that you have already seen the material. Your brain just needs cues to retrieve it. Using spaced repetition is critical here to prevent the "I learned it last week, I forgot it this week" cycle.
Previously Interview-Ready (Rusty)
Timeline: 4-6 weeks of focused review (1-1.5 hours daily)
Your muscle memory is dormant, not dead. You have done this before—you just need to reactivate the pathways. Do not re-read textbooks. Jump straight into targeted pattern practice.
The "Rust Removal" Schedule (4-6 Weeks)
Pattern Rapid Fire
Do one problem from each major pattern category: Two Pointers, Sliding Window, Hash Map, BFS/DFS, Binary Search. The goal is not mastery but to "ping" each neural pathway. Note which patterns feel rusty and which are instinctive.
Targeted Weakness Drill
Based on Week 1 results, attack your weakest patterns. If Dynamic Programming was shaky, do 3 problems a day on just DP. If Trees felt foreign, grind tree traversals. Depth beats breadth when reactivating dormant skills.
Speed and Communication
Randomized timed practice: pick random Medium problems and solve in 25 minutes or less. Talk out loud while solving, even alone. This is critical for interview day—your brain needs to explain and code simultaneously.
Mock Interviews and System Design (if applicable)
Schedule at least 2 mock interviews this week. Use Pramp, Interviewing.io, or a friend. For senior roles, allocate time for system design review. At this stage, no new algorithm learning—only refinement and confidence building.
The key insight for rusty engineers: you do not need to "learn" again. You need to retrieve. Treat every problem as a retrieval exercise, not a learning exercise. If a solution does not come to you within 10 minutes, look at a hint—then try to re-solve it from scratch 48 hours later.
The Minimum Viable Preparation (MVP)
If you have an interview in 4 weeks and panic is setting in, forget "comprehensive." You need to play the odds. Here is the Pareto Principle (80/20 rule) of interview prep:
- Arrays and Strings (30% of problems)
Most interviews start here. If you cannot optimize a loop, you fail immediately. - Hash Maps (20% of problems)
The single most useful tool for optimizing time complexity. Master it. - DFS/BFS on Trees (25% of problems)
If you can solve basic tree traversals, you can stumble through most graph problems too. - Generic Layout Patterns
Focus on clean code and communication. A messy correct solution often fails; a clean partial solution sometimes passes.
The 4-Week "Panic Mode" Schedule
Arrays, Strings, and Hash Maps Only
Solve one Easy and one Medium problem per day using Two Pointers, Sliding Window, and Hash Maps. This covers the highest-probability interview topics. Skip everything else.
Trees and Basic Recursion
Focus on binary tree DFS (preorder, inorder, postorder) and BFS (level-order traversal). Do not go deep on graphs—just enough to recognize the traversal pattern if it appears.
Timed Problem Practice
Solve problems under time pressure. Set a 25-minute timer and force yourself to code without stopping. If stuck, reset and try a new problem. Speed under pressure is a skill you must train.
Mock Interviews and Review
Do at least two mock interviews. Use the remaining time to re-solve problems you struggled with. No new learning this week—only consolidation and confidence.
Quality Over Speed
There is a temptation to "grind" 500 problems. Resist it. Shallow coverage of 20 patterns is worth less than deep mastery of 10. If you truly understand the core patterns, you do not need to memorize solutions.
The Math of Consistency
If you study 2 hours daily for 5 months, that is ~300 hours of deliberate practice. At an average of 45 minutes per problem (including deep review), that is roughly 400 problems. That is more than enough to pass a Senior Engineer interview at Google. The secret isn't more hours; it's consistent hours.
How TerminalTales Structures Your Timeline
We designed the TerminalTales curriculum specifically to fit this 3-6 month window without burnout:
- Curated Order: We don't just dump a list of topics. We teach them in dependency order (e.g., teaching Stacks before Recursion because the call stack is a stack).
- Active Recall: Our built-in Flashcards and Spaced Repetition System ensure you aren't leaking knowledge from Month 1 while studying Month 4.
- Story-Driven Context: It's easier to remember an algorithm when it saved your job in a simulation than when you read it in a dry textbook.
There is no magic shortcut. But with a structured approach, the path is clear. Stop asking "how long" and start with "what's next."
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