The foliage should be starting to die off and the peony will go dormant for the season. they should also be okay to leave out in the open, I usually don't water my peonies any more once the foliage dies off.

My peonies do not yellow the foliage until November and I do not cut the foliage until then. If you are going to plant it in the garden I would do it as soon as the weather cools in your area. Mine are planted high enough to see the buds through the winter. I leave about 6 inches of the old stem to protect next years buds from the night critters that dig in the garden. Al