We just grew out chicks and they are 8 months old now. We notice that the bulk of the body structure & weight came at about 7-8m. We even had a hen that we thought was the "runt" suprise us by filling out, at what felt like, overnight. However, their color & combs were pretty well established by the 5 m. mark. My daughter showed the 3 of them at the Stockton, Ca PPBA-NBA 2013 show and placed with one. Here's her web info, if you're interested. http://gabeyssmartchicks.weebly.com/index.html