As long as your chickens are laying, you can hatch and incubate chicks all year round. However, traditionally the most popular time to breed your own chickens is February to May.
This is because your flock of chickens will arguably be strongest and healthiest in the Spring and so you will get the best eggs. The chickens that you breed in the Spring will start to lay eggs for you in Autumn (24 weeks after they hatch).
Adam, 6 February 2016
this is very helpful