PLace this code in the applicable Sheet's Code Page
Option Explicit
Private Sub Worksheet_Change(ByVal Target As Range)
If Target.Column = 1 Then TimeStamp Target 'Calls TimeStamp sub
End Sub
Private Sub TimeStamp(ByVal Target As Range)
If Target.Count > 1 Then Exit Sub 'More than one cell changed
Application.EnableEvents = False 'Stop these changes from triggering Worksheet_Change sub
With Target
.Offset(, 1) = Format(Now, "hh:mm:ss AMPM")
.Offset(, 2) = Format(Date, "mm/dd/yyyy")
.Offset(, 3) = Format(Date, "DDD")
End With
Application.EnableEvents = True
End Sub