Introducing new chicks to flock

[AlishaC]

I am so nervous to do this but it is so much work to keep them separated...
How old should new chicks be when you introduce them to the flock?

I have 6 one-year old laying hens, (living in the same coop but separated by chicken wire) are 2, Eleven Week old Pullets, 1 Eleven-Week old Rooster, and now 4 ten- Week old Pullets...Should they all be the same size?

My 6 one-Year old Hens


The 3 Eleven-Week old on the right (raised from day old chicks)
and the 4 ten-week old pullets purchased last week.

 

[CascadiaRiver]

Well since they are different ages I doubt they would be the same sizes, I might wait to introduce the smaller chicks for a while maybe 11-12 weeks~