I am waiting for May 1 WOC dining package as well.
The general reasoning that I have been given is:
The actual WOC entertainment start time has not yet been determined, by whoever makes that determination. Unlike the regular restaurants, these special dining events are not held to the 60 day schedule, and are completely reliant on another team actually providing the schedule for the entertainment (same thing for Frozen Dining Package at Carthay Circle, it depends on when the shows take place), before they can schedule the dining or dessert event.
It's annoying, because Dining Reservations can't tell you whether the day will happen or not (even though with WOC it most likely will), so you have to check every day until it opens if you are impatient.
Also please note that WOC Dessert and Dining packages don't usually fill up that quickly...