I was in a similar situation--I got mine last night, but realized that I only had a miniSIM on hand, not a nanoSIM. So I set the phone up as much as I could without a SIM, and then went to T-Mobile today to get the nanoSIM and finish everything up. No problems for me!
By the way, FedEx was horrible with the delivery. The tracking site initially said it would be delivered last Thursday 12/3. I rearranged my day to make sure I'd be around, since the package would be left on the doorstep otherwise (interestingly, no signature needed for a $700 phone!). At around 9 PM, the tracking changed to "Delivery Exception, delivery not attempted," with no further explanation. Was rescheduled for 12/4, and the same thing happened. Rescheduled for Monday 12/7, and I called FedEx in the AM to see if it was actually going to be delivered, and the guy said yes. But the same thing happened, for the 3rd business day in a row! Finally arrived on 12/8. Complained to FedEx customer service, but they said the holiday season can cause delays. That's fine, but they really need to give more details on their tracking site, since that's all we have to go on when figuring out how to accept delivery. And 3 failed deliveries in a row is kind of ridiculous. I couldn't even ask for it to be held at the delivery station for me to pick up, because apparently Google puts a restriction on the delivery to prevent pickup. Not sure how leaving it on my doorstep for several hours is any safer.:-\
Oh yeah, the phone is friggin awrsome.