B.B.
S.,
We have told both of our daughters that they had to wait until they turned 10. Our oldest daughter turned 10 last year. After getting her ears pierced she did fine with the responsibility of the care for the ears, disinfecting, turning the earrings. However, we still had issues when it came time to change the earrings even after the "waiting period". I ended up practically shoving them through (as gently as I could) her ear causing her to cry. I felt bad but there was nothing else I could do. I would be sure that your daughter will be responsible with all of this.
Our other daughter, who is 8, thought she had to have it done also but we told her that if her sister had to wait until she was 10, so does she. Then it is more special and she didn't get it because sister did. That happens too much already.
I don't know if this helps in your decision but good luck!
B.