Bookings for a online meeting with parents

I am having trouble with the new version of bookings. I followed the new video step by step but still did not solve the issue. We need our staff to be bookable just on the 20th November from 07:45 to 13:30 in increments of 15 minutes. I go the time slots correct but as a bookable date the calendar is highlighting 30 October and not available on the 20th November.