In less than three weeks Microsoft will begin notifying users who reserved Windows 10, that their reserved upgrade is ready to be installed. According to a Microsoft blog post, not everyone is going to be notified on the first day that their upgrade is ready because the upgrade will be released in waves.
If you have not yet reserved your Windows 10 upgrade, there is a walk-through on Microsoft’s Windows 10 upgrade page.
For those not familiar with the changes in Windows 10 or curious about what’s new, Microsoft has a document titled Exploring Windows 10 available for download.
In the meantime, if you’d like to see some images of what Windows 10 is shaping up to look like, Neowin Screenshots Gallery of Windows 10 build 10163 and Windows 10 build 10159 should give you a pretty good idea.