Tealboy.
One thing that I learned hunting here in the upper mid-west. Where it can be in the minus side of the thermometer during deer season.
Don't move too fast while walking out to the deer stand. This creates sweat in the boot, and will cause your feet to get cold faster.
What I do now is walk slowly when going out to the stand, and I don't wear all of my clothes either, this too will increase body heat. Instead I carry the heaviest layers that I need to keep warm.
I also wear lighter socks to the stand and add the heavy wools before I get into the stand. I have also added a felt insole to my boots. This adds another layer of insulation to the bottom of my feet, and has increased my comfort level greatly.