I was going to maybe wait a week with mine before attempting feeding. Ideally, if it will take it, I'll try mysis shot out from a turkey baster and it will eat what it catches. My other BTA seems to do well with this. Failing that, maybe some chopped shrimp or prawn pieces in the 1/4"-1/2" size placed in the middle of the oral disk with say large tweezers or something like that. You don't really need to see the mouth, if hungry enough the 'nem will take care of the rest.
PS. Oh and once a week or thereabouts is usually fine with BTAs, at least in my experience. I've gone long periods of time without feeding them too but it's probably better to give them a little bit to work with for the first bit.