Age of pullet if adding to flock

[kscottjoyce]

Just wondering if anyone knows how old a pullet should be if being introduced into a flock of 3 hens and a rooster?

 

[Happy Chooks]

Generally, it's best if they are roughly the same size as the adults. I've integrated mine at 13 weeks, but I give them a period of time before that where they can see each other, but not interact. Then I slip them on the roost at night. The new ones do take some abuse until the pecking order is reestablished.