The required approach is not so easy to implement and requires some custom code. I have attached a simple project which you can use as a base - it demonstrates how to group TimelineView by years and by months. Note that you should manually set VisibleDays property and also CurrentDate property which defines the first date in the view.
I would suggest to show the count of the appointments in TimeRuler headers. This could be achieved by customizing the TimeRulerItemTemplateSelector of the ScheduleView. You can add the needed details in HorizontalTimelineMinorItemTemplate.
Hope this will help.
the Telerik team