WEEKDAY(date, [firstdayofweek])

Returns the number representing the day of the week for a given date (Integer).

date	The date you want the day for (Variant).
firstdayofweek	(Optional) A vbDayOfWeek constant that specifies the first day of the week (Integer): 0 = vbUseSystemDayOfWeek 1 = vbSunday (default) 2 = vbMonday 3 = vbTuesday 4 = vbWednesday 5 = vbThursday 6 = vbFriday 7 = vbSaturday

REMARKS

* If "firstdayofweek" is left blank, then 1 (vbSunday) is used.
* If "firstdayofweek" = vbUseSystemDayOfWeek, this takes the setting from the Control Panel, Region.
* If the Calendar property setting is Gregorian, the returned integer represents the Gregorian day of the week for the date argument.
* If the calendar is Hijri, the returned integer represents the Hijri day of the week for the date argument.
* For Hijri dates, the argument number is any numeric expression that can represent a date and/or time from 1/1/100 (Gregorian Aug 2, 718) through 4/3/9666 (Gregorian Dec 31, 9999).
* You can use the WEEKDAYNAME function to return the day of the week as a string.
* The equivalent Excel function is Application.WorksheetFunction.WEEKDAY
* The equivalent .NET function is Microsoft.VisualBasic.DateAndTime.Weekday
* For the Microsoft documentation refer to learn.microsoft.com

Debug.Print VBA.Format("06/07/2020","dddd")                          'Monday  
Debug.Print Weekday(#06/07/2020#, vbDayOfWeek.vbMonday)              '7  
Debug.Print Weekday(#07/07/2020#, vbDayOfWeek.vbMonday)              '2  
Debug.Print Weekday(#08/07/2020#, vbDayOfWeek.vbMonday)              '5  
Debug.Print Weekday(#12/07/2020#, vbDayOfWeek.vbMonday)              '1  
Debug.Print Weekday(#06/07/2020#, vbDayOfWeek.vbSunday)              '1  
Debug.Print Weekday(#06/07/2020#, vbDayOfWeek.vbSunday)              '1  
Debug.Print Weekday(#06/07/2020#, vbDayOfWeek.vbMonday)              '7 / vbDayOfWeek.vbSaturday  
Debug.Print Weekday(#06/07/2020#, vbDayOfWeek.vbTuesday)             '6 / vbDayOfWeek.vbFriday  
Debug.Print Weekday(#06/07/2020#, vbDayOfWeek.vbUseSystemDayOfWeek)  '7 / vbDayOfWeek.vbSaturday  

Debug.Print Weekday(VBA.Date)                                        '2  
Debug.Print Weekday(VBA.Date, vbDayOfWeek.vbMonday)                  '1  
Debug.Print Weekday(VBA.Date, vbDayOfWeek.vbUseSystemDayOfWeek)      '1  

Debug.Print Weekday(VBA.Now, vbDayOfWeek.vbSunday)                   '1, run on a Sunday  
Debug.Print Weekday(VBA.Now, vbDayOfWeek.vbMonday)                   '1, run on a Monday