Unless you are a large group, a day in advance should be fine.
Usually about a week, though sometimes you can get lucky and there are open bookings day of!
Technically, I think you only need to book at least an hour ahead of time. Practically, you should book as far in advance as you can, as this location is quite popular.
Depends on if you want to book the entire room or if you are willing to join a different group of people.
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