So if they are real production reds they would be pullets, because they would be sex linked, so they males would be mostly white.
However, as there was some doubt about it I'm wondering if they aren't actually sexlinked, in which case the only way to tell at this age is comb and wattles size/colour, and general build. I am going with pullets at this point, but if they get any more colour in their combs they might be cockerels.
At 10 to 12 weeks of age if cockerels they will get new saddle feather that will be pointed, coming though.