Bom dia!!

Dentro de um módulo de planilha insira o código abaixo.

Private Sub Worksheet_Change(ByVal Target As Range)
    If Target.Row > 1 Then Cells(Target.Row, "B") = Now()
End Sub

Att

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
If Target.Column = 1 And Target.Row > 1 Then
Range("b" & Target.Row) = Now()
End If
End Sub

CORRIGINDO

Private Sub Worksheet_Change(ByVal Target As Range)
If Target.Column = 1 And Target.Row > 1 Then
Range("b" & Target.Row) = Now()
End If
End Sub

Boa tarde!!

Eu não entendi sua resposta, resolveu?

Att