Excel cell default to todays date and time

"If you're happy writing VBA you can do this with the Worksheet Change Event.

Here's some sample code which will write today's date and time in column B whenever you change a cell in column A:

Private Sub Worksheet_Change(ByVal Target As Range)
Dim CellToChange As Range

'Check the change happened in Column A (i.e. 1)
If Target.Column = 1 Then
'The Cell we want to change is on this row, but in Column B (i.e. 2)
Set CellToChange = Target.Worksheet.Cells(Target.Row, 2)

'Only write in Today's date and the time if the cell is empty
If IsEmpty(CellToChange) Then
CellToChange.Value = Now
End If
End If
End Sub

If you need the change to happen in different columns just change the column numbers in:

If Target.Column = 1 Then

and:

Set CellToChange = Target.Worksheet.Cells(Target.Row, 2)

To get this code on your Worksheet hit Alt+F11, double click your sheet in the tree view on the left and then paste the code into the Window that appears."