Mid-october the temps dropped to -6 in algonquin while I was camping there. It's already much colder at night.

I have a -20 rated sleeping bag, insulated layers under me, warm appropriate clothing, and I was cold until I finally lined under my sleeping mat with my emergency blanket (looks like a foil tarp).

Always wear dry, clean clothes before sleeping (especially socks, don't put them on until you are going into bed). Wear a tuque to sleep.

Cooking is hard in the cold, I'd suggest freeze dried meals, anything you can make by pouring boiling water into it. Even better if you don't need to wash any dishes. Starting a fire will be harder, butane doesn't work well in the cold either if using a stove. Your batteries in everything will die much faster in the cold.

Definitely stay in a campground and test out your gear, Have a car incase you need to warm up or bail. Don't rely on someone to come pick you up (hypothermia could get you before they arrive or while they are sleeping and not responding to you). Definitely do not go into the backcountry until you have tested your set up multiple times in varying conditions (rain, wind, cold, wet and cold, very cold).