the atmosphere doesn't really matter while it is underground. no it is not much of a concern. there is variety of times needed to sprout per seed. if oyu watered properly the first time there should be no need to mist for 5-7 days unless you have a fan blasting directly at substrate.
it's better to use a smaller pot for seedlings or it forces you into bad watering habits to mitigate the large pot / small plant predicament.
don't distubr the substrate.. just have patience. it either is alive or it is not, but if you dig around and interfere you could cause a death of a seed that was 100% avoidable had you just left it alone. After 10-12 days you can start to accept it may have rotted under the soil, but not this soon.
how long it takes is directly related to depth you planted it. The other sideof that is if too shallow you'll have to take off a shell once sprouted. This is a delicate procedure that is best to avoid. This is a sign it needs to be a bit deeper.. doesn't take much.
Also, a warmer substrate (~76-82F i believe, i stick to 76) will give you more consistent results too. I grow in the winter so i need a heat mat. 2.5-3days to sprout from sowing seed for the last 30 or so. Distinctly more consistent than before, so i feel pretty confident the one thign i changed (heat mat) was the cause. before it was 3-5 days with a few inevitable laggards taking 5 days.