If he is doing this with limited time, he needs to start now. Those cute little fluff balls grow FAST!Hello and thank you for the articles!
I haven't built a coop nor set up a run yet but my dad plans on making one by the end of the month or at least until the chicks are feathered.
and welcome from France! Good luck with your new flock!
Chicks will be feathered in about 4-6 weeks. Building a coop to fit 12 chickens is no small task, nor is it inexpensive. I hope he's a talented efficient builder! I haven't seen a prefab to hold that many birds for less than $1500. If you do find one, look at the dimensions, not what the box says it will hold. A dozen chickens will need a coop equivalent to about 6'x8' minimum with additional run space of about 120 square feet... just a guideline...
and Welcome to Backyard Chickens.
to have you here with us. Enjoy your time here at BYC! 
