I think you're putting too much weight on b-school -- it shouldn't be what's dictating your decision to stay with the company/position or not.
B-school isn't a glass slipper in a Cinderella story. It's not going to transform you into someone you're not, or all of a sudden catapult you into a bevy of opportunities you couldn't get on your own. A lot of b-school grads will tell you that they still have to hustle, hustle, and hustle for jobs. It's more like a continuum, a pit stop in a long career.
In any case, whether you stay in your current position or move on is really a choice you should be making independent of your b-school plans. Do what is best for your career as if you were not going to b-school at all (because you may not get into the schools you want, or you may end up not wanting to go in the end).
I'm sure you were hoping for me to suggest when you should apply - but that is your decision based on your own life/career circumstances and what you ultimately want. And even then, your focus should be on your full-time career now and what's best for you irrespective of what happens with the b-school applications.