If you have already been accepted somewhere, then you're not looking for a 0-6 program, which is a six-year pharmacy program that accepts students directly from high school. 2-3 and 2-4 programs indicate, respectively, how many years of undergraduate and how many years of pharmacy school you would complete. Different pharmacy schools have different pre-requisites, so if you want to apply after only two years of undergraduate work, you need to be careful to complete the requirements for all the pharmacy schools you want to apply to. But more students are completing bachelor's degrees before going on to pharmacy school. There's no reason to miss out on the college experience if you don't want to!
How sure are you about going into pharmacy? I don't ask to doubt you, just that I personally changed my major three or four times from freshman to senior year. Have you worked in a pharmacy, or shadowed a pharmacist, or know one well? If you're not 100% certain that it's for you, I'd recommend finding out as much about the profession as you can while working on your pre-requisites. Also take classes outside pharmacy to see if anything else is interesting to you that you might also like to consider.
So far as the PCAT goes, you'll want to take it once you have a strong handle on all the items it tests (general biology, microbiology, general chemistry, organic chemistry, math: algebra through calculus, verbal analogies, reading comprehension, etc etc). If that is next year, great; if it's five years from now, that's fine too.
Percentile ranks indicate how well a student did in comparison to other test takers. An 80, for example, means you did better than 80% of test takers and not as well as 20%.
Anyway, congrats on getting into college, and best of luck to you!