We're hatching some chicken eggs this summer and have them in a homemade incubator. The eggs are from a farm in Langley, BC that breeds "ISA Reds and Auracanas". Our eggs are different shades of whites and browns so we should end up with a variety of types of chicks.
I got our eggs on July 7 and the incubation period is 21 days. Our incubator keeps the temperature at 99-100 and humidity at around 40%.
The "X" marks on the eggs help in knowing which side is up since we have to turn them a couple times a day like a mother hen would. The reason for turning the eggs is so that the developing embryos don't get stuck to the inside of the shell.
Anyhow, assuming that half of the eggs hatch (like in nature) and that half are hens, we'll have three hens to keep in the backyard. (Not that I'm counting them yet...)