I think that totally depends on you and what's important to you. If eating at Tusker is the priority, then keep it. I'd make a FP+ for the safari ride for sometime after breakfast to minimize wait there. If you can get to AK by 7:30 or so, you could do Na'vi before your breakfast ADR, but you need to be near the front of the line for Na'vi so you're on and off in time. Since 95% of the early arrivals will be going to FoP, you should be able to do that, but you might want to start a thread over in the Theme Parks Attractions and Strategy board asking how you get into the correct line for Na'vi.
If, on the other hand, Tusker is just a "would like to" then ditch it and focus on the rides.
Either way, I'd keep the ADR for now (you can cancel the night before if you change your mind) and keep trying to get one a bit later in the morning/day.