Across the top of your Diary page, you'll be able to see a count of how many covers are arriving every 15-minute interval and it's a great way to see when you're going to be busy throughout the day and helpful for staffing.
This will also update as you add more bookings into the diary and when you add walk-ins in live service.
Additionally, at the top left corner of the Diary page lies your 'Heads In' section. Here you can see the Total Heads (covers) still to arrive for their booking per session. This is split into Morning, Afternoon and Evening bookings so you can see if you have a busy service coming up.
For every 15 minutes:
the top number indicates the number of covers at the venue at that time
the green plus indicates the number of covers arriving
the red minus indicates the number of covers due to leave