I'm not sure if the buses will be running this early, but I believe they will. Call Disney and confirm, but I think they begin running an hour before park opening. The easiest way to get there from POFQ will be to take the bus to MK and hop the resort monorail to the Poly. I've done this to play golf.
There should be a 6:30/6:45 a.m. bus that runs especially for those early morning ADR's. You can either check with the front desk when you check in or give them a call from your room to confirm. Hope you have a great time
We've gone from POFQ to a 7:30 at 'Ohana and yes, the buses were running. I think we caught ours around 7:00, but we were worried about making it on time so I'd definitely be out there earlier than that. (We were originally going to call a cab but after waiting in line 20 minutes at the concierge desk while the cm helped another guest find a restaurant - right down to going over menus, urg - I gave up and we decided to catch a bus). Also, be sure and tell the driver where you're going. Our bus was to the MK but since we were the only ones riding he dropped us right in front of the Polynesian so we made our adr on time. THANK YOU, MR. BUS DRIVER. It's not guaranteed that they will do that, but it's nice when they do and start your day with a bit of magic.