Hey Justpickone,
There are folks flying the line that have previous experience “throwing boxes.” It probably helped, but if it doesn’t work for you I don’t think it will really hurt your chances. It sounds like money is tight and if you have a better paying gig then most will not fault you. By the time you get done with your regional commitment who knows what FedEx will be looking for in candidates. Heck, the line pilots don’t know the magic potion that gets you interviewed now. Keep chugging along and keep your nose clean and hopefully things will work out for you. Good Luck