Fill in date in specific column & Row based on cell value - excel

Question

I have received a request to fill in date based on specific status chosen (cell value) in a column representing that status.
For example if I choose a Status "Event_1" in column A from a drop down list, macro should find a column with the same name (Event_1) and fill in date in that column for the Row where the status was changed.
I only got as far as filling adjacent cell with a date when said cell is changed. I know I should probably adjust offset to a column number representing my status, however I'm not sure how to achieve this.
Private Sub Worksheet_Change(ByVal Target As Excel.Range)
Dim ColNum As Integer
With Target
If .Count > 1 Then Exit Sub
If Not Intersect(Range("A:A"), .Cells) Is Nothing Then
Application.EnableEvents = False
If IsEmpty(.Value) Then
.Offset(0, 1).ClearContents
Else
With .Offset(0, 1)
.NumberFormat = "dd mmm yyyy"
.Value = Now
End With
End If
Application.EnableEvents = True
End If
End With
End Sub

Answer 1

What about this?
Private Sub Worksheet_Change(ByVal Target As Range)
Dim ColNum As Integer
With Target
If .Count > 1 Then Exit Sub
If Not Intersect(Range("A:A"), .Cells) Is Nothing Then
Application.EnableEvents = False
If IsEmpty(.Value) Then
'.Offset(0, 1).ClearContents
'Why???
Else
ColNum = Application.WorksheetFunction.Match(Target.Value, Range("1:1"), 0)
With .Offset(0, ColNum - 1)
.NumberFormat = "dd mmm yyyy"
.Value = Now
End With
End If
Application.EnableEvents = True
End If
End With
End Sub
The only part I don't get is this one:
If IsEmpty(.Value) Then
.Offset(0, 1).ClearContents
Why? You should specify what you want to do when there is no option selected.

Answer 2

A Worksheet Change: One Timestamp Per Row
Option Explicit
Private Sub Worksheet_Change(ByVal Target As Range)
On Error GoTo ClearError
Const FirstColCellAddress As String = "B1"
Const FirstRowCellAddress As String = "A2"
Const TimeFormat As String = "dd/mm/yyyy hh:mm:ss"
Dim scrg As Range
With Range(FirstRowCellAddress)
Set scrg = .Resize(.Worksheet.Rows.Count - .Row + 1)
End With
Dim irg As Range: Set irg = Intersect(scrg, Target)
If irg Is Nothing Then Exit Sub
Dim srrg As Range
Dim sCell As Range
With Range(FirstColCellAddress)
Set sCell = .Resize(, .Worksheet.Columns.Count - .Column + 1) _
.Find("*", , xlFormulas, , , xlPrevious)
Set srrg = .Resize(, sCell.Column - .Column + 1)
End With
Dim sIndex As Variant
Dim sString As String
Dim drrg As Range
Dim dCell As Range
Dim rgClear As Range
Dim rgTime As Range
For Each sCell In irg.Cells
Set drrg = srrg.Rows(sCell.Row - srrg.Row + 1)
If rgClear Is Nothing Then
Set rgClear = drrg
Else
Set rgClear = Union(rgClear, drrg)
End If
sString = CStr(sCell.Value)
sIndex = Application.Match(sString, srrg, 0)
If IsNumeric(sIndex) Then
Set dCell = drrg.Cells(sIndex)
If rgTime Is Nothing Then
Set rgTime = dCell
Else
Set rgTime = Union(rgTime, dCell)
End If
End If
Next sCell
Application.EnableEvents = False
If Not rgClear Is Nothing Then rgClear.Clear
If Not rgTime Is Nothing Then
Dim TimeStamp As Date: TimeStamp = Now
With rgTime
.NumberFormat = TimeFormat
.Value = TimeStamp
End With
End If
SafeExit:
If Not Application.EnableEvents Then Application.EnableEvents = True
Exit Sub
ClearError:
Debug.Print "Run-time error '" & Err.Number & "': " & Err.Description
Resume SafeExit
End Sub