My experience last spring was the itohs are very hearty. If you don't see any bloom buds yet you will be fine. The foilage can take the temps. Here is a picture for reassurance.
That was March, 2014. A tree peony already leafing out sticking out of the snow. The plant did fine that year. Itohs are more hearty and tree peonies. If it is below 20 degrees and you have bloom buds I would cover the plant. Make sure to take the cover off during the daylight hours. Good luck and hope this helps ease your mind.
