
This practice as far as the UK is concerned has been ileagal for over a 100 years.
As far as I am aware the only breeds cropped youn g are thsoe where the whole ear flap is removed like some of the Russian guarding breeds.
In those cropped in countries that still allow this (most Ruropean countries have or are banning it) the ears are done at about 3 months so that their shape is apparent.