Sub DateStampCOL_M()
Dim col_G, col_M, row_counter, rows_max
col_G = 7
col_M = 13
row_counter = 1
rows_max = 10
Do While row_counter <= rows_max
If Cells(row_counter, col_G).Value = "x" Then 'if column G has an x
Cells(row_counter, col_M) = Now() 'put current date and time in column M
Cells(row_counter, col_M).Value = Cells(row_counter, col_M).Value 'replace now() with its value to stop clock there
End If
row_counter = row_counter + 1 'next row
Loop
End Sub