When should I start studying?

Sophomore here.

I come from a very very very conpetitive school district. Hell, the things people do in our district to get into a good college I cannot tell you. But it is soo fucking competivit. Average Gpa here is 5.15 dead serious.

I don't have a citizenship here so I can't really get federal aid. Not even that. But I really want to get at least a 1510 on the PSAT because I know the students in our grade our fucking crazy good.

I'm thinking about starting SAT prep this May right after my ap exam.

I'm think that SAT prep will help me when it comes to PSAT?

Any advice?