It's really tough to say, because it depends on the breed. Some breeds, you can tell much younger than others. Of course, the older the better to be able to tell. Some breeds can actually be sexed at hatch! But, I'd say that typically you cannot tell much is "most" breeds until about 4 weeks...
True, I have to constantly work on that! When I take pics for this section, I typically take MANY pics and then choose the very best (most clear) of them to post. Thanks for mentioning that - good info. to have here!
Many folks ask for feedback regarding gender/breed, yet they often post pictures that are not as helpful as they could be in allowing us to give a good opinion. Here are some basic guidelines on taking pictures that give as much detail as possible, so that those wishing to give an opinion can...