Eager users with a Nexus 7 on stock Android 4.1.2 can download and apply the update at their convenience, provided they have a few of the right tools and a little time on their hands. We have a great how-to guide available that explains how to do just that right below, just substitute in the file names included in 4.2. There's also no shame in waiting for the OTA to hit your device, as it'll surely be rolling out shortly.
How to manually update your Nexus 7 to the latest Android Version
Source: Google Direct Download;Thanks, Anonymous!
More: Google Nexus 7 Tablet Forums
Via: Nexus 7 Android 4.2 update download link now live