HankAZ
Banned
There are two key pieces of information that you need...
First, you need to know which courier your store uses... since there are only two main delivery couriers in play here, you can try both FedEx and UPS. I know Apple uses UPS, but not sure which AT&T uses.
The second piece of the puzzle is figuring out what AT&T uses for a "reference number". Again, you're going to have to guess... try your cellular phone number, your AT&T account number, any other phone number that might be associated with your account or perhaps your order number.
The key is searching the courier's site for something that matches your order... it could be simple and straight forward, or you could be looking for a needle in a haystack. But you have until Friday to find it, unless AT&T provides you that information sooner.
Good luck.
I did a little poking around, and it looks like AT&T uses FedEx for shipping.