If previous HBO special DVD releases are a suitable track record to go by, then it'll show up 6 months to a year after release. Usually by about the same time that the HBO special has shown on HBO twice-through.
I own the 'From The Earth To The Moon' and 'The Sopranos: The First Season' sets on DVD. The second season of 'The Sopranos' is coming out within the month, I believe.