After you eat food it takes between 4 to 8 hours for the food to go through your entire system, be digested and eventually poop it out.
All people are different and it also depends on the amount of food the person eats but within 4 to 8 hours most people have digested the food and have pooped it out or are about to poop the waste out.
For me food is usually passed fully through my body within 4 hours and I'm usually needing to have a bowel movement within the 4 hours after eating.
Some peoples bodies take the full 8 hours for the food to be digested and move through their system.