I would treat it like a tank. Fill it, treat with dechlorinator and let the temp stabilize. Then use some sludge buster, I bought from an aquarium, it's basically a huge hit of good bacteria, then add my fish. I guess a week before adding fish? Would use the same principle with the pond as a tank, don't add too many fish at once. Add some, then wait a few weeks to add more.
Just a guess really but it's what I would do. Can't wait to see photos. Can you please take one before you start then progression photos. Pleeeeease. :-).
Good luck.