Hi Sonia,
Welcome back to the Disney Parks Moms Panel! I'm happy to let you know that buses begin operating at least 45 minutes before park openings, so with 8:00 a.m. Extra Magic Hours, they will begin operating by 7:15 a.m. You should have no trouble using
Disney's complimentary resort transportation to make your
'Ohana breakfast reservation. You may simply take a bus to Magic Kingdom Park and then hop on a quick Monorail ride to
Disney's Polynesian Village Resort for your magical breakfast with Lilo and Stitch. The Monorail will drop you off on the 2nd floor of the Resort, and once inside you'll want to head off to your right where you'll find the check-in stand for 'Ohana straight ahead.
I'd definitely encourage you to walk around and take in all the sights, sounds, and smells of the Resort while you're visiting. It's one of my favorites!
Please let us know if you have any other questions, Sonia, and have a truly magical vacation!
Missy