she does look close to egg laying by her red comb and wattles, so I would expect her to lay soon. Many will get really talkative and loud a day or so before.
It isn't unusual for a Brahma to lay until 8 months, and I always tack a month on to expected starting dates this time of year, the bigger the breed the longer it takes to mature, your rock should have started by now, but every hen is different, as well as every breed.