The official ‘launch’ date is 17 May 2017. (It’s something of a stealth launch… keeping it secret from GCHQ and the NSA!) But the book is now live on 16 May. It will be priced at 99c and equivalents around the world for the next few days, so if you’re keen to get a copy, please go here. (The link should take you to the Amazon store in your country).
The ebook version will be exclusive to Amazon for 3 months. The paperback will be out hopefully within a week. See here for more information on the book itself.