They typically announce dates a season at a time, a season in advance. Summer dates are usually announced late winter or early spring. Fall dates are usually announced late spring/early summer... etc. etc.
It will be interesting if they host a special event during Super Celebration East, the last week of April. Likely won't be open to everyone as the site would never be able to accommodate SCE attendees. But being in the same locale, it seems like it could be host to an exclusive ticketed trail ride.