I did all my prereqs online, minus Anatomy and Physiology. I started in Spring of 2013, and am finishing up this summer (though I took a few classes I didn't need after all for the schools I chose to apply for, so if you can narrow it down you can definitely cut that time down). During all of last year, I was working a little less than full time (Peace Corps); this spring and summer, I wasn't working. So, it's doable. Actually, I think my school would've accepted online A&P, but I chose to do it in-person to get back into the swing of things. And a lot of schools DO require in-person labs, so that could be a factor in which schools you apply for.
It's definitely doable if you're dedicated and can force yourself to study for a class you never physically attend. Of course, you'll also have to have reasonably functional internet, so if you can't get online pretty regularly you could have a problem. But if you are prepared and do your online stuff as early as possible, you'll have time to figure out options when the internet goes down.
Also, this was already said, but your background will absolutely be a plus.