If you've eaten some bad food and have gotten food poisoning then you begin getting sick as early as 4 hours after eating the bad food.
Sometimes it can take up to 24 hours to get the symptoms of food poisoning after eating the contaminated food.
Whenever you get food poisoning you usually don't need any medical attention and treating yourself at home is usually good enough.
If you do get food poisoning you should stop eating anything or drinking anything for a few hours.
After the few hours then try sucking on some ice or sipping small amounts of water and then only eat bland foods until you recover from the food poisoning.
Food poisoning will usually resolve itself within 2 days.
If your food poisoning doesn't resolve itself within a few days then you should see a doctor so you can see what's going on and to be sure it's not more serious.