I think most people starts AP at 11 grade, some starts with one or two at 10th grade, my son will take AP calculus next year (10th grade) if his Algebra II/Trig has a good grade. He just told me last night he can take an AP computer science next year (an introductory course, no pre-requisit). Another AP history might be, so three. Once your start highschool, your courses are mostly mapped out.