I think it's fine, generally, but I think your DH also has a point, so you have to come to an agreement, one way or the other. You can't really pierce DD's ears if your DH is against it.
I agree that MN is very anti-piercing. I don't think that generally mums are as much against it as they are here.
There is a risk that things will not go well (ears infected, ear studs not coming out easily etc), so you should be prepared for that. If you're happy to accept the risk, then the benefits of having them done early is that young children are not anticipating the pain and quickly forget about it. If you're pretty sure that your DD will have them pierced at some point, then doing it early and the child not fully understanding the pain is a bonus, really.
My DD kept asking for earrings since she was about 4, and we've gone for it just after her 6th birthday at the beginning of the school holidays. We went to Claire's and it was done with a gun. Not perfect, I agree, but not that painful, we had no major problems and no regrets. My DD totally wanted to do it, was very brave, didn't cry. Falling asleep with earrings on was hard on the first night, DD was very aware of them and would prefer to take them off for the night if she could. Then it was 6 weeks of looking after the ears - gently rotating the earrings and disinfecting them twice a day. Not a pleasant process, from the child's point of view, and best done when the child is at home (not in school or nursery). She also missed swimming lessons for a while.
Getting out the starter studs after 6 weeks was utter pain and after trying many times with no luck and some tears, we bought eZ-Release remover which did the trick. Our second earrings snapped in half inside the earlobe at one point and we went back to the healing process for a few weeks. Really bad luck. Since then no other problems apart from losing earrings in school - DD lost three pairs so far because PE teachers ask her to take them off and she doesn't always remember to put it somewhere safe.
My DD likes her earrings, and I like earrings myself, so no regrets at all. Yes, it's not all easy, and the initial six weeks of healing take some patience and effort, but from our point of view - it's worth it. Right now DD is 9 and can take earrings in and out all by herself, and she loves it.
With regards to your possible exit strategy right now - can you tell your DD that you asked the lady at the piercing shop about it and she recommends doing it during summer holidays because they heal better in summer. Would that work as a delaying tactic? 