5 year old piercing

My sons been asking for a ear piercing for a whole year since he seen mine so I was thinking for when he’s 5 in November to get it done for him (the piercer will ask him before hand to double check if he wants to do it 100%) im fine with it - my mom got mine done when I was a baby and I went on to do my own 2nd and Third ones but I won’t do my child’s as I’d rather a professional. She says there’s no point because he messes and also because her boys (my brothers) had theirs done and they don’t wear theirs so she sees it as pointless. If he didn’t ask I wouldn’t consider it or even think about it as I’m all for them choosing their piercings but since he’s asked for a whole year I can’t see why not. My mom doesn’t want me to get it done and said she won’t be happy if I do so what do I do? I personally don’t have anything against piercings and love them. It’s not like he’s asking for his eyebrow done or anything (not that he’d be allowed anyway due to his age) or say his bellybutton like I’ve got