When can I introduce my Littles to my Bigs
My suggestion - create a temporary run so you can introduce the littles with everybody seeing each other but not being able to get to each other.
Introducing new babies takes some time to have it work well.
My littles moved to the coop a couple of weeks ago and sleep out there with a fence between them and my big girl.
They now have the pen while the chicken and ducks free range during the day. I open the gate and let everybody mingle with supervision. Before that, when the littles will still on the porch, I took them out every day to run around (they don't really go far though) and on nice days, they were in a brooder in the yard.
The big girl pecked each chick once when they were trying to share her food. Now she lets them share and she doesn't seem to much care about them. The ducks are still afraid of them. I'll spend more time/effort next week making them mingle a bit more, but I don't see my new girls exploring too much yet, so I'm hoping that will come once they are larger and pal up with the big chicken.