How young is too young to have your tongue pierced?

Yesterday for family home evening we went on a hike and when we were done we played on the playground in the canyon. Abby fell off of the equipment. She bit her tongue so hard that there is a hole in it. I had to take her to the emergency room so we could figure a way to make it stop bleeding. She is lucky that she only has a few teeth or she would have bitten it off. The doctor suggested we get a pediatric dentist to come in and look at it to see if she needed stitches. They usually stitch when the hole is big enough to put a cheerio through, you could put at least one and half through hers. I did not want them to stitch her up because they would have to put her to sleep to do it. She didn't need to have it stitched up mainly because she would have just chewed off the stitches because she would not understand us telling her not to. We thought about just putting a ring through it because she has already gone through the pain of getting it pierced she might as well get some jewelry out of it. So she is going to have a major scar on her tongue, but the good news is that we don't have to worry about her getting her tongue pierced for real because scar tissue is hard to pierce.