It depends on the night you have in mind and the size of your group. Is it a holiday? During a high crowd time frame? Or during a special event, like a race weekend? Will you have a large group or very special needs? I don't think the Dessert Party sells out in a day, but for high crowd times, e.g. the week between Christmas and New Year's, it is wise to book earlier than later. And for large groups or special needs, earlier is easier. On the other hand, we were able to book the Dessert Party one day before for the last weekend of the holiday show (very crowded!). And my food needs were addressed without problem. So it isn't impossible to get spots last minute.