Easter eggers.

[Electric Chickens]

So how young is "too young"?

 

[NatJ]

So how young is "too young"?

6-8 weeks is old enough that most males will be showing red combs and wattles by then.

12+ weeks is when many males start growing male-specific saddle feathers.

Feather patterns tend to change somewhere between those ages if they are going to.

Crowing tends to start sometime between about 6 weeks and 6 months (usually toward the earlier end of that range, but it can vary quite a bit.)

Egg laying is excellent proof of being female, but tends to start sometime between about 4 months and 1 year old (partly determined by the breed, partly by the season of the year and the amount of daylight available.)

For males, many can be identified for sure by the time they are 6-8 weeks old. To be sure of females can take a while longer, because they mostly look like "not male," which is often the same as "immature male."

The more time passes without them showing male traits, the more likely it is that they are female.