Recommended time is AT LEAST 3 months before the LSAT test date. If you are applying this fall for law school, it will be best to start studying now and write in July/August so you can focus on your applications. Of course, study time is flexible and based on your diagnostic score. If you are starting above 150, then you may not need 6 months of studying. That being said, you also don't want to cram and should spend a healthy amount of hours, so maybe starting now can help you ease in.
I personally started studying for the LSAT (properly and diligently) in May 2020 and wrote the August 2020 LSAT flex. Honestly, I wish I had more time to prepare because I felt I had more potential, but I don't necessarily have to re-write.
Long story short, look into resources now. I recommend Powerscore bibles, Loophole for LR, and Manhattan Prep for RC. Do spend money on 7Sage as it enables you to make problem sets and write PTs digitally. It takes time to figure out what works well and what doesn't. You don't want to waste time doing that and focus more on having what you need and just practicing until test day.
Hope that helps!
Edit: If you are re-writing, then you probably don't need to spend 6 months. Nonetheless, ease into it. Start now. Get the right resources. Get the LSAT over and done with in the summer.