Try this:

Sub ShowSlidesOnSpecificDates()    
Dim i As Integer
Dim d1 As Date
Dim d2 As Date
d1 = Date
For i = 1 To ActivePresentation.Slides.Count
d2 = "11/20/2012" ' Replace this with the date you want to show the slide
    If d1 = d2 Then
       ActivePresentation.Slides(i).SlideShowTransition.Hidden = msoFalse
       Else
       ActivePresentation.Slides(i).SlideShowTransition.Hidden = msoTrue
    End If
Next i
End Sub

This code should show the slide on the specified date and hide all other slides. You can modify the code to use different dates for each slide if you want.