Reserve and Pick Up Question

Hi

I've preordered my iPhone but wondered if I could get it before October with reserve and pick up.

If I reserved a phone on my Apple ID at an Apple Store, could someone else go in and collect it on my behalf? Would I need to give them the money for it to pay at the store, or do they charge you during the reservation?

If anyone has any experience with this it would be great if you could let me know how it works.

Thanks.