I've watched day old chicks hatch out with their combs obvious before their feathers are even dried. Not even large combed breeds. If a bird has a single comb it will be there even as young as 1 day old. Tiny, yes, but visible. If your birds have all flat combs, they are likely pea or rose combed. Based on the coloration and Greenfire's website, I'd say you have Marsh Daisies, Twentse, or Wyandottes, or possibly all three.
