Thank you for clarifying the scenario.
You could apply DayStartTime and DayEndTime to the DayView through DayViewSettings, please go through the following topic for more details on these:
These properties can be directly bound to properties of type DateTime defined in the ViewModel.
I hope this would be helpful.
Do you want to have your say when we set our development plans?
Do you want to know when a feature you care about is added or when a bug fixed?
Telerik Feedback Portal
and vote to affect the priority of the items