VRC Worlds starts on a Wednesday, but the opening ceremonies and the qualification matches don’t start until Thursday. I haven’t checked when VEX IQ Worlds is held, but I assume it runs from Saturday night or Sunday through Tuesday.
I’m not sure why the Kentucky Exposition Center schedule (in the post linked earlier by @AidenPyle) doesn’t include Wednesday, but I assume that either the events from Wednesday will be added to Thursday’s schedule next year, or the event schedule just didn’t mention Wednesday slate of events next year, or the people who made the schedule thought the VEX events that day weren’t important enough (or attractive enough to spectators) to include them on the list.