Jimmy S is right. I always wait at least an hour. Inspect the area where the deer was hit. If I find that I hit the deer in the guts, I will wait a few hours before trailing. The deer's circulatory system pumps almost no blood to the stomach while the deer is up and moving, and it pumps most of the blood to the stomach when a deer is bedded and digesting, so if gut shot, leave the deer alone long enough for it to lay down and bleed to death. A gut shot deer won't bleed out while it is up and moving. Check the color of blood and see if there is any tissue or hair, then you can tell about where you hit the deer by this sign. Lots of blood with white flecks and white hair is a good sign, (so is lung or heart material). Red blood with no white flecks indicates a muscle shot, red blood with white flecks/bubbles means a lung shot, dark smelly blood with stomach matter means a gut shot.