Oh, that's interesting.
For hatchlings I generally offer the tiniest live animal I can find (mouse hopper or fuzzy) and then immediately follow with a second f/t animal. (same size, thawed in warm water and nose heated under a light).
For juveniles and adults switching over usually takes much longer (months instead of a week or two). I'll only offer tiny live animals, and only once every other week, assuming that if they were REALLY hungry, they'd eat the jumbo f/t I'm dangling in front of them. It works, but it takes persistence. And it's not something you'd much want to do if you were trying to, say, raise up a sub-adult female to breeding size.