Tried mine at about 11 pm last night (missed delivery and the UPS customer center was a nightmare). Took two attempts, with a total time of about 5 minutes.
I just got an email from Apple saying my iPhone shipped with a defective SIM and they will sending me a new SIM via overnight shipping. No wonder I had to use the old SIM to get the phone to work. I wonder how widespread this problem is.
So glad I checked this thread. Thank you to whoever provided the phone number. I waited just about three hours after trying the online activation. Calling the phone number activated it in less than a minute.