sorry, I dont totally agree.
I have a hilume candler, and a very quick look, WITHOUT lifting the egg is how I do it. I only lift out any that Im unsure of, so i can look more thoroughly. Lid opening needs to be kept to an absolute minimum, and 18 days is the LOCKDOWN, so I check them at that point, as I remove the inserts and put a hatching mat in place. If you have your incubator in a really cold place, the incubator will be using a lot of electricity too, and opening the lid with such a sudden drop in temperature will affect your hatch badly. Keep inci in a stable temp room, sort of at comfy room temp...NOT under a window, or near a radiator.
I candle at 7-9 days, ish, then leave them til lockdown day, when i raise the humidity to 65% (just poka a bit of loo roll in one of the vent holes) and lower temp to 37
My brooder, I do what Teapots always says, USE A CARDBOARD BOX. small boxes when they v.young, it is draughtproof too. The when its yukky, throw it out. Simples. as they get older, use bigger boxes, and by about 3 weeks you will need a wire top to stop them flying away.