It is 90 days.
This is because it is tied to a restaurant ADR, and isn't specifically an experience that you are booking that just happens to include food (like a dinner show or CRT). It is a meal at the restaurant that will be served with a ticket alongside which will grant your party entrance to the reserved seating area when the gates open at Fantasmic.
I second the pp's advice, we haven't been able to get this package on any of the last three trips, and two of those was before they even cut back the performance schedule.