I have 2 chicks (1 rooster & 1 hen) that were hatched on June 25. I have another 13 chicks (all hens) that were hatched on July 23rd making them 4 weeks apart. The 2 oldest chicks have moved out to the coop - when the time comes, how do I introduce the younger ones to the older. I'm in NC, the days are in the 90's still and the nights in the 70's, what age would you recommend the new ones move out to the coop?