I have a young hen -- she just started laying eggs in November -- that wants to sit on eggs, on the only nest in the coop shared with 4 other hens. This just started in the last week, but when I removed 4 eggs from under her this morning she pecked me very hard! I added a rooster to the pen this morning. If she is determined to sit on eggs, they may as well be fertile. I planned to hatch out eggs in a few months anyway when the weather is warmer. I will set up a nest and brooding pen for her in the empty greenhouse away from the other hens. So, here are my questions: 1. How many days after introducing the rooster will eggs become fertile? 2. She is a large hen (half Columbian Rock and half easter egger). How many eggs should I let her try to incubate? I plan to add some silver pencilled Plymouth Rock eggs to her nest. That is the breed of the rooster and other hens. Thanks for any suggestions you would like to provide.