What do u mean yours will be delivered??????
The current thinking is that existing iPhone owners (like me) won't be able to upgrade instore, they will have to do it on-line or over the phone and their 3G iPhone will be delivered to them - in the same way that all O2 upgrades are done.
The theory is based on this information, for existing iPhone owners who want to upgrade, from the 02 website:
"This special early upgrade offer is only available online at o2.co.uk"
http://www.o2.co.uk/iphone/existingiphonecustomers
and from numerous people who have spoken to O2 staff who have confirmed that existing iPhone upgrades will not be done in-store