I have been wondering the EXACT same thing. The chicks I have I got in April. They haven't laid ONE egg.
It is driving me insane. I also have a 2 year old hen that we got for trading a rooster that was to loud. She hasn't laid a thing either, and we got her three months ago. I will be watching this thread to see what people say. Hope you have better luck with your chickens than I do!