I hit a doe in the liver lung area and it died in minutes. I thought I got a solid lung hit so I went after it in 30 minutes. It turns out I hit the liver and maybe the lungs. I would say wait 5 hours if it was surely a liver hit but if it was a single lung you'll have to start tracking right away because they can live off of one lung. I highly recommend that book, Tracking Wounded Deer. It is pure genius and is the best book on the subject. The author sure knows his stuff.