I have a number of users asking for this and can not seem to find a solution. On zimbra 6, when you go to the calendar, and view it in work week or day, the day itself starts at 8am. I know you can scroll back and see previous hours, but our university opens early, and a number of users are asking if we can default it to be earlier, or if they can change their calendar to be earlier. If you scroll back, it works, but if you go to the mail pane, then go back to the calendar pane, it goes back to 8am.
If anyone has a suggestion it would be greatly appreciated.