Basically (in a roundabout way) what you are doing. Make sure when you feed him Banjo sits, focuses on you not the food, and is given a yes on total focus, followed by a release word like "okay" before he is allowed to eat.
Mind you, if Banjo was my dog I wouldn't even be feeding him that way. I'd be making the little bugger sit patiently and calmly, and feeding him every last morsel by hand. Every scrap of food that goes into his gob would be coming literally from me.