I live in Minnesota, and drive a Lincoln LS (rear wheel drive).
I have a set of Blizzaks waiting to go on the car. I know that these are much softer made tires, and will get used up quicker if put on too soon. Being that the temps here have finally fallen into freezing…is it a good time to put them on now?
Is there snow on the ground?
My approach was always to have them mounted on inexpensive wheels and put them on myself after it snows.
Its currently 15 degrees, and no snow on the ground. We are expected to get with a mini snow storm this weekend. The “tyres” are already mounted on winter wheels, so it will be a quick and easy job to switch myself. I am assuming its quite safe to do now, but want some others opinions to back myself up 
I put mine on Thanksgiving weekend b/c I have the time then. A week’s difference won’t matter much & you’ll be happy you have them on when that first storm hits.
I’d put them on now and take them off when the snow disappears next spring. This will vary depending on where you live.
Yes. This is an excellent time. This is a safety question. You want them on WHEN it snows, not after. Putting them on now will PREVENT you from getting in an accident, and that’s what their real purpose is.
You’re risking your life to save a few bucks worth of rubber.
I agree wholeheartedly with mountainbike. Why wait if temperatures are already down to 15 degrees?
I put them on this evening. Thanks for the replies all. No snow yet! 
Now’s good. Getting lousy grip in a surprise storm can hurt. Let’s put some wear on those things. Before you sell the car.