When to provide access to nesting box?

[Rockin CR]

My coop is designed for 12 chickens (I only have 9) with 3 nesting boxes on each side. My chicks have been in the coop since they were 4 weeks old so I have closed off the nesting boxes with plywood. The girls are now 9 1/2 weeks old. When should I remove the plywood and bed down the boxes for them?

 

[Zaxby's2]

I'd say around fifteen weeks

 

[Rockin CR]

Great! That's what I'll aim for. Thanks