Chicken bald back

[jameslcfc]

I have hatched some chicks who are currently 7 weeks old. I hatched them naturally and they are still with the mother. I have them with my existing flock of 3 chickens in one run separated by chicken wire. I let them all out together in the garden and other than 1 chicken occasionally having a go they are ok. I was wondering when it is ok to put them all in together as the chicks are still small?

[Chickabee]

I think I waited til about 15 weeks last year. Then put all the birds on growers pellets for a while