Our requirement (at Blood Bank insistence) is that the infusion has to begin within 15 minutes of checkout. We had problems with nurses checking out blood products before they made sure that the IV was good and without taking vitals, then wanting to bring the unit back 45 - 60 minutes later. Their policy says check IV and vitals before coming to Blood Bank to pick up units and the short time allowed to start the infusion kind of reinforces that. The number of wasted units dropped significantly after this policy was in place.
We also use the policy shared by slsmith. If there is a delay and they bring it back after 15 minutes, we check the temp. It will probably be over, so they are asked to give in 4 hours or its wasted. An Occurrence report is filed.