The fresher the track or trail the better. I would recommend that if you get into the situation that you determine the need of a dogs assistance for recovery, such as a deer arrowed at last light with sign, to go ahead and give the dog service a call that night. If it is determined more time is needed to allow the animal to expire or other circumstances arise, trails older than 24 hrs may still be recoverable. Unless the animal drops within sight, go into every recovery effort as if tracking is going to be neccessary. Note the animals position to you at time of the shot as well as its behavior after the shot, did it jump, lunge forward,duck low, head up down, limping, dragging etc.. Mark the hit sight, and gather as much info about the shot as possible, blood, blood color, fluids hair, hair color, tissue, meat, tracks and marks. My dog and many others are trained not only to be able to blood trail, but even with minimal sign are able to track individual wounded animals. Density of game, weather, and time are limiting factors.
Guided deer and hog hunts in Fisher/Stonewall/Shackelford counties. 325-660-6652