i would give him 3-4 days atleast to settle into the tank before feeding. he needs to get his foot dug in and attached and then adjust to the tank water.
what and how i feed my 2 carpets. i go to the grocery store and get a bag of frozen shrimp (actually i get 2-1.5 for the family dinner .5 for fish food) take a shrimp and wash it off with warm water to remove its flash frozen ice envelope, then soak in some RO water for about a half hour. rinse with RO. cut the shrimp in half (at 12" you may not have too, mine take it whole now) holding onto to the shrimp firmly at one end place it onto the carpets edge about 1/2"-1" in from edge. he will grip onto it. i will give it a wiggle as he tries to pull it in simulating live prey and make him pull harder. release it and he should wrap around it and feed.
if you have fish in the tank,,,feed them first this will keep them happy and not want to try and get some shrimp (my bluethroat trigger does get his face stung once and awhile being greedy)
i feed this way appx once a week.