I have 4 hens that are 3.5 years old. In a couple weeks, I will be getting 13 new chicks (all large breeds). I have raised new chicks before, but never when I had grown hens. I won't have them coming outside until they are 9-10 weeks old. So, no worries until then. But, how/when should I try to introduce them to each other? Any personal experiences you can share are appreciated. Thanks!