The cut-off time is the latest possible time you can place a booking, you can set cut-off time for each tour by hour.
For example: If you want to allow booking only before 2 days, you will set 48 in the cut-off time value field.
Go to JB Tour => Tour, then add a new tour or click on an available tour, choose "Options and Groups setting" tab, you will see the blank "Cut-off time in hour" at the right corner.
You can fill into the blank "Cutoff time in hour" the number of total time you allow your customer booking tour if you want the notice about remaining time to book a tour always available on tour booking site (e.g. Remaining only 1 day 2 hours 30 minutes to book this tour). Your customers can't book this tour any more if there's a red text "OVERTIME" on your site. If you want to delete this text you just need change the cutoff time as longer or set cutoff time as 0 (hour).