How old are these chickens?

[codechicken1]

I am guessing around 16-17 weeks. The guy I bought them off said that they should be near egg laying age, that was three weeks ago. I have my nest boxes closed up as they started sleeping in them. They also just starting roosting, literally yesterday. No eggs yet, thats why I am asking. Thanks for any help.

 

[chicknlove]

15-17 weeks looks about right. Wonder why they just started roosting??

 

[codechicken1]

They were all sleeping in the opening to the coop.
The last three nights I physically placed them on the ladder to the roost and coaxed them up. Last night I went down after dusk and noticed two of them up on the roost. The other was on a branch in the run, don't know if she ever went in. I also noticed a depression in the floor of the coops wood shavings.