Leghorns and their kin get ridiculously large combs ridiculously early. But generally their wattles are small/nonexistant and sort of peach-colored at that age. The fact that his are bright red = cockerel to me.
Aww, shucks. Thanks.@sylviethecochin
I love it when commenters add details about why they believe a bird is one sex or another - it is such a great way to learn! Thanks for including the info on how leghorns' development timeline differs from other breeds!