The NextExtraDaysStart property is a read-only property that defines
the starting day for the set of the next month's "extra" days on the calendar. If
this property is zero, this means that there are no next extra days
for that month. This property can be used in conjunction with the
NextExtraDaysEnd property to determine the starting and ending days for
the next month's extra days.
NOTE: This property is only valid if the ShowExtraDays property is true.
