Even tho the PSATS dont really count, they do give you a pretty good idea of where you stand and how much effort you’ll need to put into the SATS.
I don’t think it’s ever too early to start studying but more in an ongoing non pressurized way as opposed to trying to cram everything in a hurry.
A lot of students have problems with the huge lists of vocabulary words in the practice tests. The easiest way to tackle that is with smaller groups of Flash cards you make up for yourself each week ALL YEAR LONG. This is the best way to truly have confidence on the vocab section.
Trying to tackle large list in the few months prior can end up being potentially confusing as a lot of the unfamiliar words can end up being confused one for another because you’re trying to cram in too much.
Taking them in smaller batches on a weekly basis all throughout the year gives you the time to familiarize yourself with them and work them into your daily life as you go along.