You could have early room service, but it is quite typical for the buffet breakfast to open early on days when the ship has tours leaving early. I'd expect to see the buffet open at 6am.
There is usually coffee, juice, milk, yogurt, muffins/pastries, cold cereal and fruit on the lido early in the morning. You can always leave an order for room service breakfast the night before, and have it delivered early enough to give you time to digest before you leave.