Interesting question. I use the zip ties & just cut them off & replace them; usually need to do it twice. If you wait until they stop growing, will you still know who is who? I'd think you'd be pretty safe to do it around 24 weeks?
I'm using yarn until they growup. I did their parents at about 18 weeks and didn't need to redo them. I haven't had to redo the yarn in a few weeks so I'm kind of hoping I can put the permanate ones on before I introduce them into the coop.
They're permanant ones will be zip ties. One color for the year and one for their individual ID.
I started banding my pullets when they stated laying around 16 -17 weeks old. I have no more than 8 in one breed/coop so I can use different colored zip ties. It was hard to use on the Cochins but the Araucanas have done well and they haven't needed changing in the few months I have had them on.
It helps me keep up with who is laying and I keep it recorded in a book. If I see who lays all the better.