If you’re still waiting for that little icon on your taskbar to alert you that your free copy of Windows 10 is ready to be installed, there’s a good chance you could be waiting quite a while. With hundreds of millions of Windows 7 and 8.1 users on more than a billion devices, the gradual Windows 10 rollout is going to take some time, and Microsoft estimates that it could be weeks before everyone gets their hands on their free copy of the new operating system.