Well don't I feel like the South end of a North bound mule!! I was looking at the wrong month!! they have been with us for 5 weeks on Sunday! Good catch Debid and no Crowing yet.Have you had them for 7-8 weeks? They look much younger. Like 3-4 weeks.
But yes, a red comb that's growing before the chick has even finished feathering is an indicator of a cockerel. Females can blush a little pink but they save the growth and darker shades for when they are near laying age.
Behavior is a poor predictor of gender unless it's already crowing.