I would try both approaches, although Le Cellier sometimes doesn't even keep a waitlist. Sometimes they are so overbooked they tell you to just go away (nicely, of course) -- they won't even take your name.
To us, however, 8 PM is the perfect time to eat at LC. You miss the fireworks, but who cares! You'll see them another time. And usually, a late ADR like that gives you a relaxed meal when the restaurant is not as crowded and frantic as it would be earlier. You also are leaving after the big crush of people leaving the fireworks, and it's a beautiful time of night at Epcot. We often walk out the long way, just to enjoy the atmosphere when the place is almost vacant.