My brown leghorn hit 16 weeks today and her (honestly, it's pretty reddish) comb has definitely gotten bigger over the past week, but with how big leghorn combs get in general, I think she still has a few weeks to go. I feel it in my gut that she'll be laying by the end of the month though. My white leghorn hit 14 weeks today and her comb is still very uncolored and tiny, so there's a big difference in how the combs look between my two leghorns and I'm thinking the white one will start laying at an older age than the brown will.