Im going to wait until she asks so I can use it as a reward for something REALLY good! Although, that is the only reason! I had mine done as a baby and do not remember any of that. My other piercings, I remember them hurting. Personally I think you should do it whenever you feel comfortable about it and not worry about what other people think. It's your baby, it's not a big deal and people that get so upset about other people's baby's ears make me LOL. Imagine them sitting there with a big stick up their butt, because that's what I envision!
If you are willing to take good care of the piercing, go to a piercing pediatrician or reputable place with a needle, then go for it. I do think you risk her ears growing differently at a very young age though.