Hello Betsy and a warm welcome to the Disney Parks Moms Panel where it's our pleasure to assist you.
You truly won't want to miss the iconic
IllumiNations: Reflections of Earth during your next visit to
Epcot and to time it just right with an Advanced Dining Reservation at
La Hacienda de San Angel would be practically perfect in every way and for certain would be a superb highlight of your trip as it was for my own family last yEar.
In my own experience of making Advanced Dining Reservations to try and coincide with IllumiNations: Reflections of Earth I always firstly double check the schedule for my intended day of visit via
Park Hours & Calendars to know the exact start time of IllumiNations. After which I check for restaurant reservation times which begin around 1 to 2-1/2 hours prior although it must be said there is absolutely no guarantee your party will be seated at a table which benefits from an interrupted view of the show; it really does come down to availability on the night but it never hurts to mention to a Cast Member that you're more than happy to wait a little longer if a table with a better view may soon become available.
As the current British Panelist I'd also like to recommend the
Rose & Crown Dining Room as a wonderful alternative and you really should try the fish & chips and mushy peas there as they truly are authentically delicious!
Have a great Disney day.
~ Jane