Every year I have November 1st as my goal date for turning on the heat. Most years I get close, and I think last year I missed it by just one day, but I really do try hard and if it was just me, I'd make it if I had to wear 15 layers.
I also have a goal date of June 15th before turning on the AC, but it's much more difficult for me to adhere to that one, especially now that I'm at that special age where I carry around my own internal furnace year-round. But add in Delaware's killer humidity and a whole bunch of rain with wind that made opening the windows impossible, I finally caved.
At least we have central air now, on an efficient system, and with a kick-ass good filtering system.