The list isn't out yet. If you want a pacakge, you are beter off picking a date and going with it just so you can be sure to get into the preferred seating, in my opinion.
If when the list comes out and you want to change dates, you can call dining up and see if there's availability. You have up to 48 hours before to cancel. I'd make a ressie now just so I had the peace of mind knowing that I had a spot sometime.