Being someone who had to get the credits done that way, here are a few pointers:
1. If at ALL possible, use dual enrollment. Pharmacy schools cannot ignore credits earned at an institution of higher learning (even if it is a CC).
2. If you are going the AP route, have adequate test scores in the AP, and I mean low scores are 4s. Pharmacy schools are pretty skeptical of high school dual enrollment science due to the lack of laboratories and the lack of time pressure involved. Don't worry, it'll make your university chemistry experience much easier. I know my school too is leery about accepting AP credit and strongly prefers taking the class at university. If you did receive AP credit, an advanced course to substitute is not a bad idea.
3. If you're really obsessed, arrange with your school to physically take the classes at the university or CC. I found that my Cal. Physics I. was easier timewise at the university than my high school's because the lecture and lab profs didn't screw around with homework, projects, and other BS.
4. Strength of schedule in high school only matters if you want to apply to PCP, St. Louis, or any of the combined program schools. Otherwise, working hard but not insane and doing the two-year (or less) college route is the way to go.
I got into the professional years straight out of high school, and I somewhat regret I didn't smell the roses afterward. Take the time also to live what's left of your high school years as well.
