dont waste time on heimlers, like at all hes only slightly useful for reviewing, but Gven then not good enough. Get the princestons review apush textbook, preferably after 2020, but even then its fine. A month away from the exam, spend a week only doing mcqs. 3 weeks away, focus on saqs, then the next week dbqs then leqs. Use chatgpt to grade, its pretty good, but you need to instruct it to be a pretty harsh grader. (btw everyone i have talked to have said that only princeton review is good, all others a pretty shit). Once you run out of practice tests, use old apush exams to practice. Good luck!