In Store?

Okay, I might have made a mistake. Last Sunday I decided to switch to T-Mobile. Got on their website an ordered 3 new iPhones. Didn't port my number on that day because I figured I would screw myself and be without AT&T service for a week while I waited for the iPhones to be released tomorrow. Anyway, new phones should be here tomorrow. Would it be best to just head down to the store and have them port my number there? I know the in-store employees work off commission. I'm assuming tomorrow may be busy for them, is there a way to tip a rep for helping us out? If so, how much do you think? Or is it a situation that I can just call the number and have them do it? I probably should've just waited and went and did everything in-store instead of online.