AP world History

So I am taking AP world history this year. Im a sophmore now. I want to get at least a 4. I am planning on getting the AP world history exam book so that I can study it. But I was wondering if I am taking the exam my second semester of school? I think it might be obvious but I have been worrying about that and idk why. Maybe its because idk if im supposed to get the 2017 book or not?