Be out at the POR MK bus stop that morning.....buses start running between 6:15 and 6:30 to MK. You can tell the driver you are headed to the Polynesian and he/she may be able to drop you there after heading to the MK. If that isn't possible, then go to MK and take the monorail over to the Polynesian..that starts running at 7am.
Keep in mind that the early morning ADR buses don't run as frequently as the regular buses...so if you get to the bus stop as one is pulling away, you may have to wait about 20 or so mins for the next one. I woud leave at least an hour to get from POR to the Polynesian....perhaps a bit more.