It depends on the size. If you have a 1" sling then 4-5 days later it may take food, but if you have an adult 5-6" of something and it molts then you would wait much longer. But looking at the fangs is a great indication if its safe to offer food. When the fangs are that light whitish red then its much to early to feed, but if they are blacked that means its nice and hard and ready to eat some more.
I normally just offer prey after a week and it prey is not taken within a few mintues I remove the item and try again in a few days.