The phones will be allocated in the order we received the preorder, so if you are 1 on the list, you will get the first call. If we have 50 preorders and 20 phones, we still reserve the phone for you, but it would just not be the day of the launch. We will call and schedule appointments to avoid this kind of situation, we don't want people to have to worry about lining up outside the door if they preordered a phone. That's just not fair to be honest, and I can relate because I would never have time to line up for a phone =/
If someone comes in before their appointment, they have to wait until everyone else gets their phone whos appointment is before theirs, and it really just messes with our pace. We actually schedule our employees to the appointment list, to make sure we have enough coverage.
So no, yours won't be sold to the first one in the door

It will have a piece of paper with your name on it taped to the box, waiting for you at the time you request to come in.
Hope that helps!