One of the best things RJ ever did to help him, and now Thomas and Maddie are doing it, is practice doing ollies on a skateboard. Do it in the grass as long as it is not too thick, in case you fall. Getting air is largely an illusion, so to speak. You are doing an ollie off the lip of the wake.
First be able to ollie on a skateboard, then be able to ollie on a wakesurf board in the flats while holding the rope, then do it off the lip of the wake. The lip is not in the same place on all boats and is more clearly defined on some more than others. You should at least be able to get the fins out of the water on the flats before going to the lip.