Phase 1 is when they start limit entry. I think (although not sure) on-site hotel guests can still go in during this phase, but it's mostly just waiting for enough bodies to leave so that they can let guests in.Just FYI: the park hit Phase 2 closing before 11:00 AM yesterday (Saturday).
Not sure what Phase 2 entails, but I think during Phase 1 they close the south parking garage.