When KB3035583 is installed, it will give user a Get Windows 10 icon at the taskbar.
User will then click the icon and make the reservation for a free Win 10 upgrade.
All that hoopla is just a marketing ploy.
You don't need it to get a free upgrade to Windows 10.
As long as you have a
genuine copy of Windows 7
SP1 or Win 8.1 with
Update 1, you are entitled to have a free Win 10 upgrade regardless of whether you have made the "reservation" or not.
You just have to wait for it.
If you don't want to wait, use this method to install Win 10.
I used the same method to install Win 10 Home and Win 10 Pro to my 2 laptops.
1. Download the media Creation Tool. Make sure you pick the correct bit version.
http://www.microsoft.com/en-us/software-download/windows10
2. Run the Tool.
Select
Create installation media for another PC option. That will create a Win 10 ISO.
(You can burn it to a bootable media later on. This method does not require it ).
3. Right click at the ISO > click Mount > click Setup.exe.
Installation will begin. This method allows you to keep your files, settings and apps.
This method does not require product key.
Activation will be automatic.