Try searching in April, May, and June, and see if there is anything. Keep checking various days, and you'll probably find availability stops completely on a particular day. Availability before this day (almost) every day, but nothing after. This will be the day it's released until.
Fantasmic packages are often not released at 180 days (unfortunately). Also, for dinner, the cut off is pretty early (4:30 or 5:00).