I've gone back and forth on getting DD's done. In the end I waited, she's asked for them done recently and I explained to her what would happen/how they are done and she doesn't want them done yet.

Personally I would NEVR EVER get them done with a "gun" and when she's ready it will be done with a needle by a piercer I trust. Those gun studs are blunt and can cause a lot of damage to the tissue, they are also impossible to sterilise.