Many contests use fairly predictable timings. CalStates seems to be the first half of March, aiming for the first weekend if possible. I would suspect Florida uses a similar mentality for scheduling.
It seems Worlds is first weekend in August, Nationals is first Saturday in October. BAC seems to be middle of May. It’s not an exact science. There almost always seems to be more than enough advance notification for people to make travel arrangements. 2+ months is usually more than adequate.