When to intergrate?

[Chicks Galore3]

I have 12 full grown hens (just over a year old) and 6 chicks. I'm not sure when I should have the younger ones join the biggers. They chicks are one month old right now, and outgrowing they're brooder. No, I am NOT thinking of having they join right now. I am going to move them out into the coop in a separate pen, so they can see and not touch. I am trying to decide how big to make their pen in the big coop. How big should they be when they meet the olders face to face?

 

[WalkingOnSunshine]

The closer the two flocks are in size, the better. We integrate at 18 - 19 weeks old, because they're mostly full grown and that's when the chicks are ready to switch from chick starter to layer ration any way.