I'm hearing that the first users to get Anniversary Update via Windows Update will be those with the newest hardware, BIOSes, and firmware. Those who may encounter compatibility issues because of drivers may get it slightly later through Windows Update, my contacts said.
On August 1, Microsoft made Windows 10 Anniversary Update available to its volume licensees in the Microsoft Volume Licensing Service Center. It also made the Anniversary Update code available to its reseller partners via its Partner Portal yesterday.
What about Windows Server 2016, which shares a lot of code with Windows client?
I've heard from some contacts that Microsoft RTM'd Server 2016 last week. But officials said recently they are not planning to launch Windows Server 2016 until late September at the company's Ignite conference, and to make it generally available around early October. I'm not sure if there is any reason for the lag beyond wanting to make Ignite the launch vehicle for the product.
Update No. 2: A few more tidbits about the Windows 10 Anniversary Update rollout schedule: