Question about comb size and age of chick

[SpeckledPullet]

I have a 12 day old Cochin chick that already has a tiny signle comb showing. Does this mean for certain it's a roo? I had really wanted a pullet and am worried it's a roo. The rest of my chicks are wyandottes, so I have no other cochins to compare.

 

[jeslewmazer]

I would worry if the comb get to be a bright red at an early age, but there are still pullets that do this to. It might help if you post a pic for everyone.