I currently have 11 hens that are 13 months old and 2 weeks ago I recieved 15, 1 day old Easter Eggers.I only want to keep 4-5 chicks so in a couple of months I'll be rehoming the rest of the newbies. I have a couple of questions; How big should I make the grow out pen? How soon can I put the new chooks with the established flock. I'd like to build the grow out pen right next to the main run so they all can interact through the 1/2" hardware cloth. Any other tips, advise or suggestions would be greatly appreciated. Thnx folks.