Most corns defecate within three or four days after a meal if their enclosure temps are good. But sometimes it takes longer. It varies depending on the snake too. I have a few snakes that are on 7-day feeding schedules that almost always crap in their feeding tub after eating. Also keep in mind that there isn't always a 1:1 ratio of feeding to defecating. A snake may crap a couple of times off the same meal.
Snakes don't urinate. They expel their urate waste as a solid (usually somewhat moist though). This is the white stuff you see in snake waste. It's the same with birds.