What would happen if a rooster bred a hen that wasn't old enough?

[C&Rman]

I have a 2 year old banty rooster that hasn't had a girlfriend in about a year! I found a Egyptian Fayoumis hen for sale that was born at the end of March. If I buy her and let my banty rooster and her hang out and he bred her or tried, what would happen? Also do Egyptian Fayoumis go broody? I would like to get a hen that goes broody.

 

[HEChicken]

Most male animals respond to hormones/pheromones so unless the female is exhibiting signs that she is ready to breed, they won't bother. However in the event he was particularly randy and did try to breed an underage hen, approximately nothing would happen. She would either submit or fight him off, but if she's not laying or producing eggs, there is nothing to be fertilized.