I had to wait until I was 12 and in retrospect I am glad my parents made me wait. I believe that any sort of body modification should be the choice of the person being modified. I think that if I ever have a daughter I will 1. wait for her to express a genuine desire to have her ears pierced and 2. make sure she is at an age where she can take responsibility for the cleaning/turning etc.

I feel uncomfortable with the concept of piercing a childs ear lobes for a purely asthetic effect. I don't judge those parents who have made the decision on their child's behalf, but it is not a decision I would personally make.

ETA: I really strongly suggest not going against your DP's wishes. Imagine if the shoes were on the other foot and you didn't want them and he went behind your back? It is a pretty deceitful thing IMO and I'd hate for it to cause a fight between you two.