We have 16 Buff Orps. They are almost 21 months old. They started laying just after 5 months. Up to this winter, they were pretty good layers... We would get about a dozen a day, even through last winter. I started keeping track last August, and the average was 6 per day, with a range of 3 to 10. Which means, on average, each bird is laying 2-3 eggs per week.
Of course, some might not be laying at all. I bought a dozen Red Stars in September, and two have started laying at 15 weeks old. Come spring-time, I'll start testing the Orps to see who the laziest layers are, and transfer 5-8 of them down to Ice-Station Alpha.
The Orps are really nice birds. During the warmer months, we would usually have one or two who were broody, and just wanted to hang out in the nest box all day. After a few weeks of evicting them anytime we caught them, they would snap out of it, just in time for the next one to take over. We have one rooster with the 16 hens, and only one time did he make an aggressive move... I forget what I was doing, but I remember raising my foot up in front of him, and he jumped up and hit the bottom of my shoe with his spurs. I chased him down and carried him around like a football for awhile. I've tried to egg him on a few times, but he's never done it again.