How far in advance do I need to reserve?

Generally, in the busy season (July to August) reservations should be made at least 5 days in advance or earlier. In the off-season (June & September), you should be ok to reserve the day before. However, the season could be busier than expected and it is difficult to predict how long in advance you should book. Reservations are definitely recommended as soon as you know when you wish to come.