I have 2 guns I use during season. My carry gun and ammo I let sit out side and cool for a half hour before I shoot my first shot. It is usualy cold up here in N.D. by the first of Nov, so the gun comes out of the truck warm. Then I wait a 1/2 hour between shots. I usualy have other guns to work with so waiting is not a problem. I only worry about my elevation at this time, as the wind WON"T be the same by the time you finish.
The other gun I use is my 1K match gun. It never leaves the warm cabin, so I test it first out of a warm pickup/hard case, or, if I can't shoot it right away, I shoot one warm up shot first.
Also, I usualy chrono my cold shots. When things warm up I gain around 30-50 fps over the average of a cold gun! This is very important at four digit ranges. A gain of 40 fps at 1000 yards is a 1/2 min gain in ele. in my gun. Keep that in mind if things don't go as planned and you need to fire multiple shots.
All of my guns are zeroed at 300 yards. And I either use the hash marks or dial up for anything over 400.