We have a roo and hen Belgium d'Uccles who are about ten months old. How will I know that my hen is ready to lay fertile eggs and when does this typically happen. It's early March and the weather in upstate NY is beginning to warm up. What should I be looking for? She now lays a few eggs per week and she's in her own partition area away from the standard sized hens with the roo in our coop. Thanks!