Supposing you create a dummy WMV file and point a publishing point at
it, setting the broadcast start time as a WallClock value 8 hours
after expected stream start.

http://msdn2.microsoft.com/en-us/library/ms755434(VS.85).aspx

Make that publishing point public (i.e.not requiring authorisation)

Now create a second publishing point to accept the stream from the
encoder - set it to Archive on the server, to the dummy filename you
created earlier. You could ensure that's not available (guessable) to
the internet by setting authorisation for the stream.

Once the encoder has finished, the complete file should be archived
and available for on-demand streaming, with the start time determined
by the WallClock value of the public publishing point.

In theory, the on demand PP could be trying to read from the file as
it's being encoded if you tried to overlap stream times, but AFAIK
that won't cause a problem on the server unless the user tries to fast
forward that stream to / past it's live endpoint.

You can lock that behaviour on the server to prevent that though
http://msdn2.microsoft.com/en-us/library/ms782509(VS.85).aspx
or by using a client side ASX playlist.

To get a similar-to live performance, make sure advanced fast start is
enabled so the client end gets to begin playing the content ASAP :
http://www.microsoft.com/windows/windowsmedia/technologies/bettertogether.aspx#a
dvancedfaststart

HTH
Cheers - Neil
------------------------------------------------
Digital Media MVP : 2004-2008
http://mvp.support.microsoft.com/mvpfaqs