I can't speak for this year but last year I placed an order online to use AT&T Next but I had to wait 2-3 weeks as I missed to pre-order. Decided to stand in line on launch day for the 6 Plus and once I placed a reservation, I then went to my order status and canceled the one I placed online and immediately got my eligibility for Next back instantaneous. I'd check your AT&T account and look at the status. If it hasn't, I'd say contact your AT&T CS and see if they can manually override it.
Speaking of that, I'm pretty sure there is an AT&T tech at the apple store. I just saw one today for those who are having issues.