VbFirstWeekOfYear

First-week-of-year selectors used as the firstweekofyear argument of date functions such as DateDiff, DatePart, and Weekday.

Constant	Value	Description
vbUseSystem	0	Use the setting from the system regional settings.
vbFirstJan1	1	Start with the week in which January 1 occurs (default).
vbFirstFourDays	2	Start with the first week that has at least four days in the new year.
vbFirstFullWeek	3	Start with the first full week of the year.