Yes, buses will be running early enough. We were just at MK last Sunday for an 8:05 at CP when the MK didn't open until 9am. I believe the CM at the concierge desk told me that buses for MK began running at 6:20 am. A bit early, if you ask me. But we caught a bus at about 7am from POFQ and made it to the MK in no time. If buses are running from the resorts, I can't imagine that the monorail isn't running as well.
So, you'd have a couple of options:
(1) Bus from your resort to MK, then bus to GF
(2) Bus from your resort to MK, then monorail to GF
(3) Another option you'd need to verify -bus from resort to MK, boat to GF. I'm not sure how early the boat starts running.
Personally, I'd go with #2.