Have you joined the Windows Insider program? If not, Bing it and join. Once a member, go to your Windows Update screen and scroll down to advanced tab. Click and make sure it says FAST in the "How do you want to install downloads". Go back and click to check for updates. It should show the update in just a few minutes.
Hope this helps. You can also Bing for the link to Reserve your Win 10 upgrade and sign in there should you just want to make sure you get the upgrade when released.