Taking the chance of bumping a deer is the major risk, if you see the deer die then I wouldnt wait too long. A liver shot depends on where and how much of the liver is cut as to how lethal the shot is. If you hit the hepatic portal vein or hepatic artery your deer will likely bleed out within several minutes, however if you dont hit a major artery or vein it will likely take a while for the deer to die.