This convention should get as much lined up as possible, but like haterobics said, there's a real risk that booking a show booth may fall through if a show closes. And shows booking now would be too early. Unlike known people/celebs in other industries who can book appearances far ahead of time without worrying about other contracts (e.g. authors), an actor probably shouldn't book now and then go for auditions that would force cancelations due to other obligations.
What I expect are other industry pundits and vets setting up the informational panels and workshops at least. Star autograph tables and actual performances probably won't be until later.
I do know that other conventions start ticket purchases long before the guest list and schedule are complete, but those are established events (hotel packages can sell out for the bigger conventions months ahead as well, even without a known schedule). It's entirely possible, due to theater actors' iffy schedules, however, that this convention will be forced to continually update until the last moment. I wouldn't be surprised.
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