Hello - I am interested in moving from AT&T to a shared Verizon plan with my wife who is already on Verizon. I would like to pre-order the new iPhone 6S. My contract with AT&T ends 3 days after the current ship date for the iphone. However, I can't seem to pick a different shipping date, so I am worried the port request will go to AT&T while I'm still on contract and they'll charge me the early termination fee.

So, my question is when does number porting occur for a pre-ordered phone - when it is configured before shipping or when I open the box and request the phone be activated?

Thanks!