How young can I trim wings?

[Kellichick]

I've got 12 babies, ages 5 days to 4 weeks, in an upcycled baby playpen. The older ones are starting to fly. How young can I trim wings? I've trimmed older birds before, but not these small ones. Any answers or advice is greatly appreciated. Thanx!

 

[kidd42]

I am having the same issue with my Leghorns who are about 5 weeks. I finally trimmed them this morning. But........I don't know if I trimmed enough as they are still flying up to the top of the brooder.