Microsoft has confirmed that the free upgrades to Windows 10 will be rolled out in several "waves," with beta testers getting first dibs on the OS.
Windows 10 Enterprise and Windows 10 Education, editions available only to volume licensing customers, will be ready to download on 1 August, three days after Microsoft releases Windows 10 Home and Windows 10 Pro.
"Starting on July 29, we will start rolling out Windows 10 to our Windows Insiders," wrote Terry Myerson, the top operating system and devices executive at Microsoft, on a company blog today. "From there, we will start notifying reserved systems in waves, slowly scaling up after July 29."
Windows Insider is the firm's name for the preview program that debuted on Oct. 1, 2014. Insider will continue after the launch of Windows 10 for those who want to live on the bleeding edge of change.
While at least some Insider participants -- perhaps all -- will get the final build on Wednesday, July 29, others eligible for the free upgrade will have to wait as Microsoft slowly expands distribution. Myerson did not elaborate on the timetable, so it could be days, weeks or even months before the push ends.
Such release "throttling" is not uncommon: Both Google and Mozilla do the same with new versions of their Chrome and Firefox browsers. Although Myerson touted the practice as good for customers -- "Each day of the roll-out, we will listen, learn and update the experience for all Windows 10 users," he said -- the tactic also reduces the chance that Microsoft's distribution servers will be overloaded and become unresponsive.
Microsoft is also using a new approach to deliver Windows 10 to those running Windows 7 Service Pack 1 (SP1) or Windows 8.1 Update (the mandatory update issued in April 2014): People who have "reserved" an upgrade through the on-screen nag-and-notification campaign will be told that their devices are ready to update only after Microsoft has silently pushed the bits to their machines.
"If you reserved your copy of Windows 10, we will notify you once our compatibility work confirms you will have a great experience, and Windows 10 has been downloaded on your system," said Myerson.
Neither Windows 10 Enterprise nor Windows 10 Education will be treated in that fashion for the simple reason that they are not part of the free upgrade offer. Corporations and organizations that want to migrate machines to the new OS will instead use the upgrade rights inherent in their Software Assurance plans to move to 10.
"Volume licensing customers will be able to download Windows 10 Enterprise and Windows 10 Education on Volume Licensing Service Center (VLSC) starting on August 1," Myerson said.
Analyst expect few companies to immediately jump to Windows 10 -- many of them only recently wrapped up their migrations to Windows 7 and some still have Windows XP to purge -- but IT administrators may want to begin testing the OS against their line-of-business applications, or even launch small pilot programs stocked with adventurous employees.
OEMs (original equipment manufacturers) -- the Lenovos, Dells and HPs of the world -- will get Windows 10 "soon," Myerson added, so that they can begin pre-loading the OS on new systems. Some, such as Dell, have pledged to start selling Windows 10 PCs on July 29.
Microsoft also will distribute Windows 10 to retailers before July 29, so that they can prepare for upgrading customers' recently purchased Windows 8.1 PCs.