Hey there, Sharon! You've packed three of my favorite things into one question - spring break at
Walt Disney World, breakfast at
Tusker House Restaurant and the best attraction ever (in my humble opinion) -
Avatar Flight of Passage.
As they say in
Pandora - the World of Avatar, Sivako! That's Na'vi for "rise to the challenge." You have an early morning reservation at Tusker House. You should arrive at the podium 15 minutes prior to your reservation, but because your breakfast is early, you should be seated relatively quickly. There is even a chance you could be seated a few minutes prior to your 8:10 reservation. That's a good thing.
In most cases, I would say it will take an hour to dine at a character meal so that you can meet all of the characters. In your case, as soon as you arrive at the restaurant, scope out where the characters are.You might be able to guage it so that no one is at the buffet when the characters are approaching, but if worse comes to worst, someone can be the designated breakfast platter maker, and the other grown up at the table can take character photos.
Because it's a buffet, you have some control over how long it takes you to eat. I'd recommend leaving yourself 15 minutes to walk to Flight of Passage from Tusker House, so you want to make sure you are wrapping up and paying your bill no later than 8:50. There's a chance you won't see every character, but it's enough time to eat a decent breakfast.
Good luck, Sharon!
Anna