I know this is old, but i agree with Curt, this is normal expected behaviour in the real world.
We have a meeting room booking system. If we show the timeline with the current time as starting, then the user cannot scroll back - which happens when they postpone their meeting, and just want to drag it to the right time.
If you take any outlook calendars, they are able to go back in time just fine...
So the normal operation, is the user opens the timeline scheduler for each meeting room in each row. Now they all have to start by scrolling to the current time because most bookings are now and forward.
Another problem using the startTime (.StartTime(new DateTime(DateTime.Today.Year, DateTime.Today.Month, DateTime.Today.Day, DateTime.Now.Hour, 0, 0)) ) is that it remembers the hour - so going forward to the next day, i cannot go to 8am.
Hope this is still being read by someone