I started my baby BPs on live mice - just to make sure they had a couple easy meals in them - and switched over to F/T after a couple of successful feedings. Never had a problem with the switch.
Also, I just throw the F/T mice into a bowl of hot water - I don't even worry about keeping the mice/rats dry. Never had a problem with this approach either, but YMMV. I got this idea after attending several feedings at the Cape Fear Serpentarium - where they feed all their snakes with dripping wet F/T animals... I at least take the time to wipe off excess water before offering them to the snakes.