Got an offer last month (L4, payments team, remote). Started prepping for the Stripe interview about six weeks before the loop and made a bunch of inefficient choices early. Writing what I wish I'd done from day one.
What I actually did (not ideal)
First two weeks: grinding Leetcode, mostly medium-hards. Paranoid about the coding rounds. This was partially wasted effort. The Stripe coding interview isn't about Leetcode hards. I did not see a single problem that required a niche data structure or textbook algorithm. What they actually test: clean code, edge case thinking, clear communication about complexity, and whether you ask clarifying questions before coding.
What I'd do if I started over
Week 1-2: Solve maybe 40-50 Leetcode mediums, timed. Not for memorization but to build the habit of thinking out loud and not panicking. Do them with a timer and narrate your reasoning.
Week 3: System design. For Stripe specifically, read about distributed payment systems, idempotency (this comes up a lot), exactly-once delivery, and retry logic. Not just abstractly. Understand why these matter for money movement. Read the Stripe engineering blog if you haven't. It's actually good.
Week 4: Behavioral. Stripe's behavioral round is not filler. I spent almost no time on it until the week before and I think it almost cost me. They ask things like: tell me about a time you pushed back on a decision. Tell me about a time a project failed. These require real answers, not generic STAR templates. Practice with a real person, not just notes.
Week 5-6: Mock loops. At least two full mock interviews end to end. The coding problem you can solve in your head is not the same as the one you can solve while talking, on video, with a stranger watching.
Misc things that helped
Read about Stripe's products before the recruiter screen. Not so you can name-drop, but so you understand the domain. When I got a system design question about payment retries, I had context that made my answer actually coherent.
Also: the recruiter was upfront about the process. If yours gives you a prep guide, take it seriously. I skimmed mine the first time and had to go back and re-read it more carefully.
Six weeks is enough if you're focused. Four is tight but doable.