What area in Oklahoma are you in? Most of the instructions for peonies will work in Oklahoma. In the panhandle I would add more humous or compost to where you plant. In the red dirt area I would add even more since that type of soil seems to cake very badly. Peonies have lived on the Great Plains for a couple of hundred years now at temperatures of 100+ to -40 so most of your state should be no problem. If it was a dark red planting where the sun from noon on is not directly on the plant can help the blooms last longer.

I do suggest that the first winter a inch or so of mulch be placed on top of the plant to keep from heaving. By the time the ground has settled and the rain/snow have started decomposing the mulch your plant should be at the proper depth.

When your baby starts to bloom cut some of the blooms when they are starting to soften, marshmellow stage to take in for enjoyment. One of those oddities is that when the full double peonies bloom heavy storms are generated which can remove every petal on the plant. Leave some blooms on the plant just in case.