Normally I would say 12 to 18 hours then throw the pinky in the trash and wait a few days a start over.
However, this is off topic because it is a honduran milksnake. I have one hatching that will wait 48 hour before he will eat the pinky. I highly do not recommend this to anyone because the pinky is already rotting before he eats it. I may have to go back to force feeding him or buy a pinky pump. The only way I found this out about him is that I forgot him after I say the pinky in with him after 12 hours and the next morning went to remove the pinky and it was gone.
Love the Fatman