I have two BO hens that just started laying at 27-28 weeks old.. They have been laying really well for two weeks only missed one day.. They were small to start with, but with in three days they are almost at a large egg..
My BO started at about 25 weeks, the lazy scamp! And she only ever laid a maximum of six days out of seven. And was broody within nine weeks. She hatched a single chick after eight weeks (we fought her stubborn broodiness for five weeks before giving up and getting her some fertile eggs) and she started laying again today... the hatch was nine weeks ago! She's a year old at the end of October and will have only laid for a total of twelve weeks in that time, averaging five eggs a week.
So she's not the most prolific egg-layer ever
(She's still my favourite hen though, I'll be honest. So dopey and docile. She loves cuddles!)