If you have at least some working knowledge of calculus (enough that you could look up something in a text if you needed a particular integral/derivative), then you can knock out all of the science pre-reqs in one full year. I knew plenty of non-science majors who went through their post-bacc programs at the same pace that I did and got similar grades.
(As an aside, I went through Georgetown's post-bacc program. It does not guarantee admission anywhere, but it is ideal for career changers or anyone who lacks the basic science courses or needs a refresher.)
I would advise taking a courseload as heavy as possible while still making As. If that means that you can take gen chem over the summer, then orgo/bio/physics concurrently during the school year while preparing for the April MCAT, then so be it; if you have to work, or if you think you'd be better served by taking two classes at a time instead, then that's what you have to do. Don't waste your potential by sandbagging your coursework, but don't set unrealistic goals either.
BTW, on the good, bad, & ugly -- it appears that the "good" would be a Z06. 😉 Life could certainly be worse, couldn't it?