I would just plant it now, in the permanent location. I would not trim anything. If the flower opens, enjoy it, then cut before it goes to seed. Removing any foliage takes away food production, that will feed the roots which may have been broken or lost the feeder threads. Roots will need time to regrow, so leaves can help keep plant going. Root won't have to waste energy sending up new sprouts or going dormant until next year, maybe with no food stored from lack of foliage.

Anything that turns brown, can be trimmed off. Peonies are pretty tough, when located into a nice new home. I leave all the foliage alone, until it withers up, to trim off. Good luck, lucky to be in the right place for a new plant!

I'm a little late here, but I agree with the poster above. I too moved peonies when in bloom (bulldozer coming the next day) and was successful. I still have them now, 6 years later. I planted them in the ground where they still are. Peonies really don't like being moved so potting them would just add one more step. Also I left all foliage and blooms on. When done blooming I cut off spent blooms to prevent seed pods from forming.

Good luck.