Considering Microsoft's Build 2013 developer conference is at the end of June, it's likely that the preview will be released at that time. Larson-Green also said that Windows Blue preview will be available to anyone with Windows 8 via the Windows Store.
According to previous tips and leaks, Microsoft is close to completing what's believed to be the second internal milestone build, known as the Milestone Preview, of Windows Blue. Shortly after that, Microsoft is expected to make its one-and-only Windows Blue public preview available to consumers. Earlier this week, Microsoft officials said to expect the company to make Windows Blue available by holiday 2013. I am still continuing to hear Microsoft is on track to release to manufacturing (RTM) Windows Blue by August 2013 or so.
Larson-Green says that Microsoft will be "principled but not stubborn" about modifications to Windows 8. There have been rumors that the company might bring the Start button and boot to desktop options back; however, that has not been confirmed.
In March an early version of Windows Blue leaked online. You can check out a video of that here. Microsoft is also expected to unveil a smaller 7 to 9-inch tablet at the Build Developer Conference.