Without a reservation, they have had some excellent offerings at Sanaa (Kindani side of AKL) starting around 7AM. Also, The Mara (next to the Jambo pool) has some really good offerings, coffee, and sweets! They usually open 7-7:30. And there's always the best breakfast on site, but the toughest to get a ressie for - Boma. They open at 7:30.
If you have a car, there's a McDonald's about a mile up the road, near All Star Resorts. They're probably open earlier.
Hope that helps. Enjoy AKL - it's our absolute favorite resort anywhere, not just WDW!