I'm surprised they didn't move you up already. My two brothers and I were moved up two weeks to be able to upgrade to the 6. My parents got their iPhone 5's at the end of december 2012 (29th and 31st) and both are showing as eligible right now. They moved my parents up over 3 months so it's not out of the realm of possibility that they do it for you. We didn't ask btw.
The retentions department can change your upgrade date. Last year I purchased a 5S in October and after calling them, they offered me the upgrade with 2-year contract pricing, and no upgrade fee , but I had to order from them directly. I ended up choosing the Next program and they unlocked my 5S. It's entirely possible but they will tell you that you have to order the phone from them.
I tried upgrading 2 weeks early and they wouldn't let me. Just kept pushing NEXT. My wife's contract is up 10/6 and I asked a couple days ago to move it up so we can use the trade in promotion for $200. But they said no.