Should i take my SAT as a highschool freshman or wait ?

My brother is taking it the PSAT and got a 2100 so he has SAT prep books and he will let me borrow them the thing is i went to really crappy schools their teaching wasnt sufficient for me they were not strict whatsoever, in a way they slacked off should i study hard with the things my brother has (oh yea i moved away from the crappy schools into a new neighborhood and my grades improved a lot from C's to A's and 1 B but i still feel that the school is not strict enough to really have made much of a difference in my grades do you understand ? Anyways should i wait or take the SAT's PSAT etc.