First I want to make it very clear each parent must decide what is right for their child!!!!!!! Being a parent is the most important job out there! I love my 3 children! That said, here is what we decided!
My DD was 14 when she had her belly button done! She asked and we talked it over! We decided it was not a life changing decision so it was ok! One condition was she had to go with a parent it was her Dad that went with her! My DH checked out the shop and made sure it was 100% safe! He was present the entire time! We all thought she would chicken out but nope!

Today she is 22 and has upper and lower done! Also her upper ear and targus. No tatts. we discussed this over the years and I feel thats life changing because you have a tatt. forever! She now agrees tatts. are forever! Its funny to hear her repeat "the talk" to soemone! As a side not a piercing can be removed and forgotten! My DD is a special education teacher now! I am very proud of her!
In the end its your decision as a parent!
Just my thoughts! Different choices for each family! No right or wrong!!!!!