the method is exactly the same however you select month + day:

Code:
Dim monthString As String = "_" & now.month.ToString("00")
Dim month As XElement = xml.Root.Element(monthString)
If month IsNot Nothing Then
    Label1.Text = month.Elements("_" & now.day.ToString("00"))(0).Element("Morning").Value
    Label2.Text = month.Elements("_" & now.day.ToString("00"))(0).Element("Noon").Value
    Label3.Text = month.Elements("_" & now.day.ToString("00"))(0).Element("Afternoon").Value
    Label4.Text = month.Elements("_" & now.day.ToString("00"))(0).Element("Sunset").Value
    Label5.Text = month.Elements(("_" & now.day.ToString("00"))(0).Element("Night").Value
End If