Windows 10 Anniversary Update is due on August 2 and will be delivered to the current installations of Windows 10 that have been running for at least 30 days. It’s 3GB update that is going to take some time to download and install.
By default, the big update will be downloaded automatically when it becomes available but it can be delayed if you don’t want to get on the wagon right away.
Go to Settings → Update & security, and Advanced options in Windows Update.
Then check the option “Defer feature updates” that takes your PC out from the Current Branch which gets feature updates as soon as they are released to the public) and move it to the Current Branch for Business.
When you defer upgrades, new Windows feature updates won’t be downloaded or installed for at least four months until Microsoft declares that they are ready for the Current Branch for Business. The Defer feature updates option doesn’t affect security updates. You will still continue to get regular security updates as usual.
Note #1: the option is only available in Windows 10 Pro and Enterprise editions. Home editions will always get the updates automatically.
Note #2: the option is called “Defer Upgrades” in version 1511 but called “Defer feature updates” in Anniversary Updates.