@Giovuhnni I'm doing the IB too! I don't know how they do IB at your school, but I wouldn't recommend getting the AP prep book -- some of the syllabi are pretty different, actually! The main ones I can think of are Math HL and Calc BC; even though they're equivalent courses, HL covers some topics not covered by BC and vice versa.
A common book to get for the IB are textbooks by Cambridge/Pearson/Haese (for math) and doing a ton of practice papers from question banks online.
I got several books for Christmas! My favorites are The Birth of a Theorem (Cedric Villani) and the Math Book (Clifford Pickover)! The former's structured more like a novel whereas the latter is similar to trivia books (one topic per spread?). I've also heard great things about xkcd's Thing Explainer, which looks interesting!