As I always tell everyone just do whatever you can afford because this is a process and you need to come in consistently for optimal results. Of course it would be great for every bride to be completely hair free for the big day but it is not always monetarily feasible.
If there are a few areas that are really bothering you or that are really hairy I wold suggest on starting on those areas first. We do not have to be completely done with the sessions by wedding day but we do have to schedule the session right around the big day appropriately. It normally takes 10 days or so for the hairs to shed so I suggest coming in for that last appointment before the big day 2 weeks before so that the hairs will all shed by then.
If you would like to do one or two (or more) other areas at least one time before the wedding day we can do so also- but again if you are going to invest in the treatment then it would be great that you make sure that your budget will allow for you to finish those areas after the big day.