ok i'm going to insert my opinion here. I personally waited until my daughters were old enough to ask, and i let them wait for several months after the discussion to make sure that is what they wanted. They were 7.
However, when i was in high school i had a job as an ear piercer at Claire's Boutique. I remember Christmas time there were line's out the door for parents getting their childs ears pierced. And i cannot tell you how many crying children and babies i pierced. I never quite looked at as abuse per say, but i was uncomfortable with the idea. That is why i waited on my children. My brother and his wife had their daughter's ears done when she was a few months old. I disapproved but i don't think it was abusive.