He has a nice little comb coming in. Very cute!
If he is a standard, you'll probably want to rehome him. He could easily hurt one of your bantam girls without meaning to.
Welcome to BYC.
Until you know whether he is a standard cochin or a bantam, this is impossible to answer.
I would say raise him for a few weeks and reevaluate. Also, all "teenaged" cockerels will aggrevate hens, until they get a little more mature, though some hens may keep them cowed. At...