Since I have a group of snakes. Food gets offered every week, and whatever gets turned down in five minutes-immediately goes to a different snake.
I would only offer once every 2 weeks unless I saw signs the snake was restless.
In the old days when I had one snake: after a rejection I would put my f/t rodent in the refrigerator and pray they would eat it in a few days on another try-otherwise I was out of luck and the crows got a snack.