An even better approach is to empty the fish into a net and drop the fish straight into the quarantine tank. As long as you have good conditions in the tank, e.g. warm temp, clean water, etc., its always good to bring fish into ideal conditions asap. How would you rather be treated, if you've been stored at sub-zero temperatures in a foul environment, and are within five minutes from death? Do you want to be gradually thawed or brought back to 72F asap?