if this is an Enchanting Extra, this is the policy I found on the Disney Website
Q:
When can I make advance reservations for experiences at Walt Disney World Resort, such as dining reservations and available Enchanting Extras Collection experiences?
A:
Guests may make advance reservations for dining and
Enchanting Extras Collection experiences (like tours and recreation).
When to Book: Dining
- Guests with a Valid Disney Resort Hotel Reservation: Make reservations for your entire length of stay (for up to a 10-night stay) up to 60 days in advance of your arrival! This can help you enjoy streamlined vacation planning, since you can make all your reservations on the same day—rather than checking availability day after day.
- All Other Guests: Make reservations up to 60 days in advance.
- At approximately 6:00 AM daily, new reservation booking windows become available for select Walt Disney World restaurants.