Excel VBA - Do not execute if - vba

Question

This is my Macro for a time stamp:
Private Sub Worksheet_Change(ByVal Target As Range)
Dim WorkRng As Range
Dim Rng As Range
Dim xOffsetColumn As Integer
Set WorkRng = Intersect(Application.ActiveSheet.Range("N:N"), Target)
xOffsetColumn = 6
If Not WorkRng Is Nothing Then
Application.EnableEvents = False
For Each Rng In WorkRng
If Not VBA.IsEmpty(Rng.Value) Then
Rng.Offset(0, xOffsetColumn).Value = Now
Rng.Offset(0, xOffsetColumn).NumberFormat = "mm-dd-yyyy, hh:mm:ss"
Else
Rng.Offset(0, xOffsetColumn).ClearContents
End If
Next
Application.EnableEvents = True
End If
End Sub
I did not write this originally. I found it off of a forum as my macro knowledge is primitive at best.
Essentially I would like the time stamp to ONLY OCCUR ONCE so I need this macro not to run if a time stamp already exists in column AK.

Answer 1

I think this does what you want. It checks if AK is blank - if so, it adds the date, if not, it does nothing.
Private Sub Worksheet_Change(ByVal Target As Range)
Dim WorkRng As Range
Dim Rng As Range
Dim xOffsetColumn As Long
Set WorkRng = Intersect(Application.ActiveSheet.Range("A:A"), Target)
xOffsetColumn = 36
If Not WorkRng Is Nothing Then
Application.EnableEvents = False
For Each Rng In WorkRng
If Not VBA.IsEmpty(Rng.Value) Then
If Len(Rng.Offset(0, xOffsetColumn)) = 0 Then
Rng.Offset(0, xOffsetColumn).Value = Now
Rng.Offset(0, xOffsetColumn).NumberFormat = "mm-dd-yyyy, hh:mm:ss"
End If
Else
Rng.Offset(0, xOffsetColumn).ClearContents
End If
Next
Application.EnableEvents = True
End If
End Sub