Additional question:
What happens with activities booked outside these hours? Are they not viewable?
For me, the ideal layout would be to slide the hours so that the first time shown is, say, 8AM, but with an ability to view scroll up and view earlier appointments if they exist.
So, if I set the day start time at 8AM, what happens with a meeting booked from 7AM to 7:30 AM. It wouldn't be visible, right?