Typically, publishers send advance review copies to the press anywhere from four to six months before publication date, but some wait until the book is published. (buildbookbuzz.com)
Some publishers use digital printing initially for advance review copies to test their market and, if the book does well, switch to a larger print run on a press later. (bookdesignmadesimple.com)
The logistics of contacting reviewers with advanced review copies and making sure they can download the ebooks to their readers of choice. (marketingsff.com)