Go get 'em!
Android 4.3 has only just been announced, but Google has already published the Android 4.3 factory images (build JWR66V) for the Nexus 4, Nexus 7 (Wifi and 3G), Nexus 10 and Galaxy Nexus (yakju and takju variants).
These are images that allow you to directly update (and wipe) your device, installing the new OS from scratch. So if you don't want to wait for the OTA on your Nexus, you can now go the manual route. Download link's below — enjoy!