I've had three hatchery Light Brahmas for just over 8 months, raised from chicks. One was the first of all my hens (4 breeds) to lay, before the Production Reds, before the Rocks. So much for being a late laying breed. She is noticeably smaller than the other two LBs, and so are her eggs. She and the biggest LB (who lays the biggest eggs) are regular layers, but the third is a sometime layer, with really odd-looking eggs. She was one of my last hens to lay.
All this to say...expect the unexpected.
P.S. If my Pip keeps growing until she's 18 months, I'm not going to be able to lift her anymore!