at about 6 months out the males will grow spurs the females might but they are much smaller the males heads will be blockier , if you wait too long in the spring to seperate them you will find out witch ones are the weakest males this might help a little
The spurs is right although some females will have spurs but you can tell by the beak too males are wider and more red. Also I've heard but never attempted that you can take a caliper at day olds and a leg over 2cm is male and under is female.