Hi Michael,
Thanks for using syncfusion products.
In order to start a Schedule control with particular day, you can use MonthCalendarStartDayOfWeek. This property gets or sets DayOfWeek that is shown in the left-most column of the month calendar.
Code Snippet
this.scheduleControl1.Appearance.MonthCalendarStartDayOfWeek = DayOfWeek.Sunday;
The below properties can also be used for changing the start day of NavigationCalendar and WeekCalendar.
Code Snippet
this.scheduleControl1.Appearance.MonthCalendarStartDayOfWeek = DayOfWeek.Sunday;
this.scheduleControl1.Appearance.WeekCalendarStartDayOfWeek = DayOfWeek.Sunday;
ScreenShot
Please refer the below KB,
Regards,
Pavithra K.