You can change the MonthView.FirstDayHeaderDateFormat
property of the Scheduler. You can also refer to the Customization
demo where this and most of the other properties are shown.
Hope this will be helpful.
the Telerik team
If you want to get updates on new releases, tips and tricks and sneak peeks at our product labs directly from the developers working on the RadControls for ASP.NET AJAX, subscribe to their blog feed