You need not be in any rush to take Math 16A, since you already have AP calculus AB.
You may want to start your pre-med courses with Physics 8A and perhaps Statistics 131A, since they are not duplicative of your AP courses, and your AP calculus AB should fulfill their calculus prerequisites. Then, if you later decide not to do pre-med, you will not have wasted any courses repeating what you already know. (However, you probably want to start chemistry no later than this spring.)