I want a 5s and want it as soon as possible. So I'm thinking of getting up at 3 AM CDT to order when it goes on sale Friday. However, I thought about trying my luck at walking into a store on Friday and potentially finding one. I know that's a longshot, but if I have already pre-ordered one, will my upgrade already have been used due to the preorder? Or will I be able to upgrade in store, then come home and cancel my preorder.