Her's an example of how one function can check the daters of all date TextBoxes.
Private Sub txtweekc_Exit(ByVal Cancel As MSForms.ReturnBoolean)
 'Sample Date TextBox Exit Event Sub
Dim CancelMe As Boolean
  With txtweekc
    .Text = CheckDate(.Text, CancelMe)
  End With
  Cancel = CancelMe
 End Sub
 
 Private Function CheckDate(ByVal DateString As String, ByRef CancelMe As Boolean) As String
 'Check date format of DateString, Set CancelMe in Calling Sub
 'Returns formatted date if input DateString is good, else returns Empty String
        If IsDate(DateString) Then 'Format as desired.
            CheckDate = CStr(Format(CDate(DateString), "dd/mm/yyyy"))
        Else
            CheckDate = ""
            MsgBox "Please enter a valid date."
            CancelMe = True
            Exit Function
        End If
         
         'Test for date in correct range
        If CDate(CheckDate) < Now - 30 Or CDate(CheckDate) > Now Then 'Between 30 days ago and today
            CheckDate = ""
            MsgBox "Please enter an allowed date."
            CancelMe = True
        End If
End Function