Once the den is made they should start eating within a few days.

My Bluespots have fed fine with large fish. What food are you trying to feed? I have the best luck with Rod's food or mysis shrimp for the Bluespots, but the yellowheaded jawfish may do best with smaller brine shrimp as a starter food. If they have been fed from a feeding tube in the past they will do fine with it, but if they haven't they will hide if you use one. You can aim your pump so it gently directs water past but not into the den.

As a general note, when possible, cooler temps, lower salinity, and low light also help them acclimate to a tank easier.