Tarantulas eat about once every 2 weeks. People give tarantulas up to three crickets in one feed. Sometimes though, tarantulas are given food one time a week and then have food in another 4 days. Then a tarantula might be feed in 8 days after that. There's not really a set timetable for feeding a tarantula.
Tarantulas also eat mice, lizards and other small animals depending on the type of tarantula. If a tarantula is put with say a mouse which is too strong for it, the tarantula might get hurt or even killed.
If a tarantula does not eat its food within 24 hours, the food should be taken away. The same applies for when a body part like a limb of a cricket is left in. This is because parasites can get in and go onto the tarantula as well.