If you say something now, after only the first time, it would then be hypocritical of you to ever have a party.
I mean if it was on a regular basis, yes fine complain, but if it's just once in a blue moon you really don't have anything to complain about.
Remember that you're going to have to live above this person after you complain and that they could get very petty.
I've got a 18 year old girl living next me, with a very bad taste in music
EDIT: What I'm trying to say that it's swings and roundabouts.