I did a lot of prep before & created WDW pages each park had its own folder with attractions & shows having pop ups.
The parks are massive sensory overload but I found that I could model a lot and having things visually helped regulate.
I didn't insist on full sentences when choosing activities and he did use it to make choices including telling us he needs to leave one day.
You can see from the posted pictures we has a packed few days. The daily schedule was updated as we went around the parks.