Best time to switch is after they lay in general they will eat anything however as it seems that you have a true finicky eater it does not mean she will eat better just a different food source.

Having a true picky eater is frustrating but the more animal you own the more you are bound to have one and trying alternative preys is rarely the solution.

I have a picky female that eats maybe 3 or 4 months out of the year that's just the way she is.