When and how to start selfstudying?

Hi, this may be posted elsewhere but I’d rather have a direct response. I’m a senior taking 4 AP classes but I’m going to selfstudy the Psychology test. It is February 7th which means I have a little under 3 months until the test. I have the Barron’s book and the Princeton review. I’m not sure exactly how to self study since I’ve never done it before. Should I just read each book cover to cover over the span of 3 months? And experience or advice is helpful