What is the latest for dog ear cropping?

When is the latest time that anyone should get there dogs ears cropped, or does it matter what kind of dog is is because mine are 2 pitbull's

Should be done by 12 weeks old. With a very short crop you can go as late as 16 weeks but earlier is better. Breed does mater as different breeds have different crop lengthsAdd: despite what one poster seems to think cropping is not illegal in any state of the US

ear cropping should be done before 12 wks I believe

As far as I know, it's illegal in most states now.