Alterar as cores dos controles dependendo da data em VB.Net

Public Sub AlteraCorDeFundo(ByVal Formulario As Control)
     Dim ctl As Control
     For Each ctl In Formulario.Controls
         Select Case System.DateTime.Now.Day
             Case 9 To 11
                 ctl.BackColor = Color.Black
                 ctl.ForeColor = Color.Yellow
                 Formulario.BackColor = Color.Black
             Case Else
                 ctl.BackColor = Color.LightGray
                 ctl.ForeColor = Color.Blue
                 Formulario.BackColor = Color.LightGray
         End Select
      Next
End Sub