schedule a code to run once a week

Hello forum,
I found this code in a different forum where it is scheduled to run once a month:

Private Sub Workbook_Open()
Dim bError As Boolean
Dim iLastMonth As Integer
Dim datLastRun As Date

On Error Resume Next
datLastRun = ThisWorkbook.CustomDocumentProperties.Item("LastRunDate")
bError = Err.Number <> 0
On Error GoTo 0

If bError = False Then iLastMonth = Month(datLastRun)

If iLastMonth <> Month(Date) Then

    MsgBox "run your macro here"
    
    With ThisWorkbook.CustomDocumentProperties
        If bError Then
            .Add Name:="LastRunDate", _
                LinkToContent:=False, _
                Type:=msoPropertyTypeDate, _
                Value:=Date
        Else
            .Item("LastRunDate").Value = Date
        End If
    End With
End If

End Sub

i love this code because it stores the last run date in some inner library so that if the day was missed it will still run the next time the workbook is opened, but i don't know how to make this code run once a week. I can get it to run once a day because excel recognizes the code word "Day", but excel will not recognize the word "Week".
Any help on this would be greatly appreciated.

Thanks!