KHV is known to have a lifetime of approximately 24 hours without a fish host. Like others said above, some of the fish parasites can live for a significant period of time without a host, at least a day, for some several days, for a few a week may be possible.
Certainly a week hold time will dramatically reduce the possibility of a virus or parasite contamination.
Be aware however that birds, frogs, and a variety of other wildlife can bring parasites to the pond. The normal sources are new fish, new pond plants, and fresh lake water.
President Truman said, "If you can't stand the heat, get out of the kitchen." And he said if you want a friend on the AKCA board, better take your dog to the board meeting with you.