For the first time I would get it done about a week before the event - it should be fine for about 4 - 6 weeks.

Reason for a week is the first time you can get little whiteheads (not huge, just a few) and they will go away after a few days. It will also feel numb for a day or two.

sadly, I think lip waxing hurts the most but at least it is over very quickly - unlike bikini/g/brazilian