10 is officially getting released on 7/29. Microsoft would like you to reserve your copy, & doing so means the bits would be downloaded to your PC/laptop ahead of time, so on the 29th you just click the install button basically. To make sure you know this, they've installed an app, if you installed Windows Update KB3035583, that sits in the notification area of the Task Bar.
1 The 72% saving is based on one M32ts Azure VM for Windows OS in US Gov Virginia region running for 36 months at a Pay as You Go rate of $3660.81 /month; reduced rate for a 3-year Reserved Instance of $663.45 /month. Azure pricing as of (prices subject to change). Actual savings may vary based on location, instance type, or usage. Microsoft has started advertising Windows 10 to Windows 7 and 8 users with a popup that allows the user to reserve their copy of Windows 10 by following the instructions in the prompt. And how to get the 'Reservation App' working when it doesn't show in the taskbar. How to get the Windows 10 Upgrade on the taskbar. (only available for Windows 7 SP1 and Windows 8.1 Update 1).
Windows 10 Appx Packages
Windows 10 Reservation App
You can hide the app through the customize option in the notification pop-up, but then it'll appear in the list of running apps. You can uninstall the update, or you can kill the gwx process in Task Mgr.