You will be picking up the device in the Best Buy store ( if u went down that road) which will call u for the pick up. That's how it works. When u pick it up, they will ask u to pay the remaining amount in person at the store.
Now I have pre-order from best buy and roger. Rogers will never let me upgrade, unless I cancel the order. Do you have idea how cancellation pre orsy work and how much time it takes? Consider that's iPhone launch date. It's hard to get hold of any customer care we executive.