If you come by private car then you don’t need to pre-book. There are set tour times:
11:30
12:30
13:30
15:30
On the High Holiday days there are additional tours at
10:30
14:30
Last tour on Fridays is 13:30
First tour on Shabat (Saturday) is 12:30
Private groups and Tour Company groups must pre-book a time, (which can be outside of the set tour times as well as at the set times). If you don’t book you may find there is no time slot available for you to enter. The first available booking time is 8:30am as it takes time to drive from the entrance (open at 8am) to the Tabernacle and to disembark.
Also if you want to change the time or day please stay in touch with the Tabernacle staff. This is very important, especially if you are running late.