Use the recommended oil from the manual for the expected temps. With lighter oil, keep a closer eye on oil consumption.
Before the heated garage, I parked the 446 next to the truck with the truck plugged in. Could start the truck to boost the 446.
A primer bulb or electric fuel pump are good aids for cold weather starting...saves cranking to get fuel if the tractor has not run for a while.
Once you get the engine running and warmed enough to run with the choke off, continue to warm it up at 3/4 throttle with the transmission in neutral and travel lever in forward...this will help warm the oil, drive motor and rear end. How long will depend on how cold things are.
Before you start blowing, cycle the blower up and down...if it's cold, it'll move pretty slow at first but will get faster as warmer oil gets to the lift cylinder.
My yard and driveway are gravel, I keep the blower up a little the first couple times. This keeps most of the rocks out of the blower, and eventually results in a layer of packed snow...I call it my "base". With the base established, the blower will largely glide right along. If you have trouble steering, lift the blower a tiny bit to put more weight on the front tires.
Think ahead about where you're blowing snow TO...it's a bugger to move a mountain of frozen snow three months into winter.
Snow in the face kinda sucks...learn to work with the wind.
Al