After plucking and cleaning, we submerge the birds in cold water until no body heat remains. They heat up the water and we add more cold. I don't think we do this for rigor mortis reasons. We feel it compromises the safety of the meat to throw it in the freezer without first removing as much heat as possible. Plus it makes the freezer work really hard to put 10 or 12 birds in that are still warm. So for the sake of freezer efficiency and cold meat being safer meat, we cool, cool, cool. But we cool for an hour, maybe hour and half, sometimes less if bird is smaller. Have never waited 24 or even 4 hours to get a bird in freezer.