BCGSuite for MFC
void CBCGPCalendar::SetFirstDayOfWeek ( int  nDay)

Sets the first day of week.

The first day of week displayed in the most left column of the month. Set this parameter to (-1) for the default (system locale) value.

nDaySpecifies the first day of week. It should be an integer in the (inclusive) interval [0-6] or (-1) - default.