you would be fine, even getting an app--we were just there, party of 3, at 7:30 on a Saturday night in May when they were packed. We were in and out in about 75 minutes-- and all 3 of us had adult beverages, apps, entree, desserts & coffee. Every table was full, long wait list time (90 min. without a reservation) But we were seated within 10 min of checking in..we had a reservation.
When we've had early ressies, which we usually do, they're usually not even beginning to get busy until 6:00. You should have little or no wait at that time, and then when you're done eating, you're right next to the exit to the monorail so quick trip to the park. And remember, once you walk into the park, you're right there for Spectro.