The period is 0.5 months to 1 year, 0.5 months. - Edit 1
Before modification by Aeryn at 21/08/2010 01:04:07 AM
Not to mention - we're talking hardcover release. People who wait for paperbacks will always be behind and just miss your dates cutoff.
Though this is true even so, depending on how fast the paperback is released.
For example, The Gathering Storm</I> came out in October 2009, the paperback isn't out yet, and won't be until late September.
Wings of Wrath by CS Friedman came out in paperback in February 2010, and in hardcover in February 2009.
House of Suns by Alastair Reynolds came out in paperback in late May 2010 (I haven't had a chance to buy it yet, although he's one of my favorite authors), and in hardcover in June 2009 - and this was supposed to be one of his best novels yet.
So you see, for most publishers, it's exactly a year between HC and MMPB release. And if I can't afford hardcovers, then I would have only had a chance to buy the books which were released in the month of August 2009, and had less than a month to do it in - the buying and reading.