My understanding is that, as you say, peonies should be planted in the fall. However, the big stores like Home Depot and so on sell them in the spring! I couldn't resist last year and bought one in the spring, but on DG Peony Forum's advice, I kept it all summer and planted what looked like a half-dead plant in the fall, and forgot all about it. (When it didn't emerge this spring, I decided next time I would plant right away, no matter what kind of advice I got.)
Then last week, I saw the rosy-green shoots poking up! Perfect timing on your article, and thank you. I should have known better than to doubt DG advice!!! Now I need one of those supports. Thank you, Toni!