I do understand your wish to feed f/t however I always recommend anyone to feed the same type prey for at least 4 to 6 feedings before attempting any switch.

Remember that changing environment is stressful for a BP, and keeping one thing constant (like feeding) is always a good idea.

Get him to eat for you first, make sure he eats with consistency for you and than try to switch him.

Your priority is to get him to eat for you first and foremost, switching is secondary.