When should I let my 9 week chicks live with the adult hens?

[Appalachickens]

Sure, I think it's a great time to incorporate them. My little ones are usually out with the adults full time by 6 weeks or so. Just take it slowly. The pullets might get a few warning pecks and freak out lol, but it likely won't hurt them. I usually keep the separator door cracked just enough so the little ones can retreat but the big ones can't follow.

Btw love your cute coop! Oh to have flat land like that for building! Everything here is on the side of a mountain, which is gorgeous but makes everything (including walking) difficult sometimes.

Steep land here, too - I had a heck of a time finding even a moderately level spot and had to shoehorn in a coop and run.