I recommend adding this type of Booking in Advance logic directly to a Calendar or Time Slot list.
So you would use the Get Available Time Slots element normally, and then filter it’s results to exclude Time Slots that are within that un-bookable time. The plugin gives you more flexibility when you pull in slightly more time slots then you directly need, and then you can fine tune exact filtering within your own logic instead of the Plugin’s logic - and the performance is essentially the same.
An example of where I would add this type of ‘hours in advanced of booking logic’, and use the same constraints when you display the List of Time Slots when the day is clicked:
