I've been the first guy to get cold feet since I was a kid. As was said above keep the rest of you warm, if core temp drops the blood flow to feet and fingers cuts off first to compensate.
Extra socks, special socks never worked for me. All they did with proper fitting boots was cramp my foot and diminish circulation. Only thing that worked was wearing boots one level of insulation greater than everyone else. Now I have several levels to choose from starting with 200 gram boots for upland to pacs that I use for ice fishing.
What I wear is always a balancing act. Morning sitting gets more insulation. But if I have to walk in a ways I'll pick a pair that I know will keep my feet warm til the planned break if no longer. Then as strategy changes I'll go to a lighter pair of boots. And keep a change of socks handy in case you misestimate and your feet sweat.
A bit of a juggling act and a PITA in general but that's the only thing that works for me.
Maybe I'm doing it wrong but chemical heaters in boots do nothing. They require air (oxygen) to work and rammed in a boot they don't get enough to make a difference.
(Have some bunny boots inherited from my mailman uncle, they were a favorite in the day among mailmen walking routes. They are horrendous compared to boots of modern construction.)
Have some other ideas like insulation under your feet while sitting, and a down vest or chemical heaters covering the kidney area. That's where I feel cold creeping in. But in eastern SD strategy changes as the day wears on and we're never more than a half-mile from a road. So the basic strategy works well.
