I would wait at least a week -- and then feed him on whatever day works best for you.

My BP was 6 months old when I got him, and was eating live up until that point. I wanted to switch him over to f/t. I talked to the breeder, and he said my snake had a really good feeding response for him. He suggested I try the f/t switch on the first feed. I took his advice, and got lucky -- he took the thawed mouse on the first attempt. (He didn't actually strike it, I ended up leaving it in the cage, and the next morning it was gone.) After that he strikes them and eats great.

Try a f/t the first time or two, if no luck, you should probably feed live just to get some food in him -- and then maybe give it another go.

Just my $.02

Later,

George