Hello Domenic!
It's wonderful to hear that you have been happy with the advice from the Moms Panel! And Tonga Toast certainly a wonderful indulgence!
Bus transportation generally begins one hour prior to the time the parks open. You'll want to check the
park hours for your specific day. If Magic Kingdom opens at 8:00, you'll have no problem. I would recommend being at Pop Century's bus depot by 7:00 to catch the first bus over to Magic Kingdom. From there you can hop on the resort monorail and exit at the Polynesian.
If the Magic Kingdom opens later, don't worry...just check with the front desk the day before your breakfast and they'll make sure you'll have transportation to get to your breakfast.
By the way, in case you didn't know, Tonga Toast is also served at Captain Cook's - the quick service dining location located at the Polynesian.
Enjoy your Tonga Toast!! Diane :)