Cochins can be difficult to sex. I would say a rooster just because of the pink comb and wattles. My Cochin is going on 8 weeks and has a yellow comb and no wattles yet. My Cochin has been feathering very slowly. She didn't start to feather until 4.5 weeks of age.
I have a RIR that has had a pink comb and wattles since 5 weeks and fully red by 8 weeks, but I think she is in fact a hen. My RIR is almost 3 months with a small red comb and wattles. I haven't heard any crowing yet, but it could be a couple more months before that happens. My RIR acts like a hen. I believe it just matured early. Time will tell.
I've tried to look when I give them their weekly looking over, but haven't really noticed anything. It is hard to see through all those foot feathers though. I'll try to look harder the next time I check them