Based my own experience if it does not die in sight give it at least 6 hours or more. I shot a nice six point and he stood unphased after the shot almost as if I had missed. He walked about 15 yards bedded and I watched waiting for the head to start bobbing, but it never did. After an hour on the bed he got up, walked across a field of switch grass and disappeared out of sight. After an additonal 5 hour wait we found him piled up 150 yards from the bed. If I would have pushed I probably would have lost him. It is tough to wait but it puts the odds of recovery in your favor.