Unless my computer is betraying the true color, that comb is awfully red. The Black Cochin is either getting ready to lay very soon, or that's a cockerel.
I have a seven year old Black Cochin hen, and she's a magnificent huge ball of black down. Your Cochin looks like a pullet in profile, and a smaller version of my big black girl.
At five months, if this is going to be a rooster, you would be hearing comical attempts to crow by now, or you will very soon. Have you heard any weird noises lately coming from your run, especially first thing in the morning?