at that age, you should be able to tell. The cockerels will have ear lobes that will probably be a bluish color and more wattles. Pullets should only have a slight wattle. The cockerels will also have a larger more pronounced comb that is very visible on their head, the pullets should be mostly covered by her feathers. The cockerels will also have more pronounced feathers on their tale, where as the pullets should only have the fluff.