Waiting for eggs

[Quetzalcoyote]

I have 3 ISA's that are about 5 months old. Hopefully, they will be ready to lay soon. I have a big nesting box that is communal. After I put the chick out in the coop a few months ago, I had to block off the nesting box with some plywood to keep them from nesting in it. Now that they are getting ready to lay soon, when should I remove the plywood and let them roam in and out of the box? Should I wait for the first egg?

 

[five is my dog]

i would open it now and put three golf balls in each nest to show its for eggs not nesting