I think you should apply to start in summer/fall 2015, which means you start applying anytime after summer 2014. Most schools will allow you to apply while you’re still finishing up a few pre-req’s, but each school has different requirements about this. As for the math classes, you’ll have to check with each school to which you’re applying and see what they’ll accept. This and this are good resources to use when deciding to apply to PT school, but ultimately it’s a good idea to check in with each school to which you’re applying.