Can anyone tell me if reservations for specialty dining are usually available on embarkation day? We are traveling with 3 couples total ... I'm late in the game to get reservations at our preferred specialties. (First time cruising since January of 2020 and things have changed a bit, first time on Celebrity with a group.) Also when I do find one available for 6 people, it requires prepayment. We'd like to use our OBC, but are afraid if we each make our own reservations we won't be seated together. On another related question, if we would purchase the 3-night dining package, is the only way to make reservations once on board? What if there is no availability?