Ellie97--
I have two barred rock pullets. I got them at 5-months old, and they started laying at 6-months. The eggs are becoming more frequent, one of them is just about up to an egg a day now. My research stated 4 eggs per week for this breed, or maybe more if they are 'hatchery' chicks to start.
so maybe not 'early bloomers' like the sex links--- but just in time bloomers (is there such a phrase?)-- and expected to have a longer laying life.