How to customize the date format of WinForms DateTimePicker (DateTimePickerAdv)?

private void dateTimePickerAdv1_Enter(object sender, System.EventArgs e)
{
   this.dateTimePickerAdv1.CustomFormat = "dd/MM/yy HH:ss";
}
private void dateTimePickerAdv1_Leave(object sender, System.EventArgs e)
{
   this.dateTimePickerAdv1.CustomFormat = "dd-MMM-yy HH:mm";
}

Private Sub dateTimePickerAdv1_Enter(ByVal sender As Object, ByVal e As System.EventArgs)
   Me.dateTimePickerAdv1.CustomFormat = "dd/MM/yy HH:ss"
End Sub
Private Sub dateTimePickerAdv1_Leave(ByVal sender As Object, ByVal e As System.EventArgs)
   Me.dateTimePickerAdv1.CustomFormat = "dd-MMM-yy HH:mm"
End Sub