3 months ago. Again, I do deep research for every company I apply for (e.g., search for employees in linkedin, check glassdoor reviews, check for potential code tasks in github, read the company/employee blogs, etc.). The research could take me several days up to a max. of one week (because more is just too much info too). I tailor (to a degree) the cv for the job (I try that at least I do have experience with 50% of what they ask, but let's say they ask for Python and I have mainly Ruby experience, well, I dedicate a week or so to brush up on Python and then I swap Ruby for Python on my cv. This doesn't work with every tech stack, of course, but works for the mainstream ones).

Another "trick" (common sense from my point of view) is to schedule if possible the first interview in the middle of the week. Typically I would schedule for a Wednesday/Thursday so that the second interview can land on the next Monday or Tuesday, that gives me at least 4-5 days to prepare for it. I try to avoid first interviews on Mondays because then it's more difficult to schedule something for the following week. I also notice that interviews with engineers scheduled in the afternoon (between 2 and 4pm) are rather "softer" than those in the mornings (I don't know why, perhaps everyone is just a bit sleepy after lunch perhaps?). I wear a white t-shirt to avoid any kind of subconscious prejudices on the side of the interviewers (you never know what kind of people are on the other side of the screen). And many more "tricks". I know that the core of the matter is to pass the challenges, but I do care about every single detail. I write down exactly how I'm gonna introduce myself, I prepare in advance potential questions like "tell me a project you've worked recently" to the point that I feel super confident talking about them. I don't leave anything to chance, but of course I may fuck it up sometimes (and I did 4 months ago in the systems design interview).

In any case, I could easily submit my cv dozens of times, but I find that preparing exhaustively for a couple of weeks for 1 or 2 jobs works best for me (based on previous experience. I have worked for around 5 companies so far in my entire career).