How to study Princeton Review Books?

I recently received my 7 Book Princeton Review Study Book Set in the mail. How should I go about studying the content? Currently I’m in the reviewing info phase and I’m not sure how in depth I need to go. Do I need to study every concept and fact mentioned in all of the 7 books (each book is 500 pegs) or do I focus only on the high yield? Currently shooting to take the exam either this September or January of next year. I have a hard time deciding between whats important info in each section and which is minor info that doesn’t need to be gone over.