I keep getting weirdly mixed signals from friends in the industry. Right now, I've been told that all small parks and attractions are ramping up and are simply waiting for the green light from the county, who has since deferred them to the state. Everything from Island H2O live to Fun Spot fits that description. However, the game gets a bit different when it comes to the big three. For the big three to open, one of them will have to be the first to pull off the band-aid. I personally doubt any band-aids get pulled before mid-June, and if we are looking at mid-June, it will be Universal or SeaWorld. The only question in my head is if SeaWorld still has enough market leverage to pull WDW and UOR out of hibernation.
To be honest, my educated guess is that we see smaller attractions/parks reopening late-May/early-June. By mid-June, testing starts at the Uni parks, signaling to other major players that it is time to get ready. By late June/early July we have our first park open, most likely a Uni park, but maybe SeaWorld, and then Disney isn't too far behind with the rollout of one or two parks.