The OTA (over the air) updates are already pushed through
Google has just released the Android 4.2 Jelly Bean factory images for some of the newest Nexus devices now available on the market.Those who own the Galaxy Nexus, Nexus 4, Nexus 7 and Nexus 10 can now download these images here.
Keep in mind that these factory images are only available for some variations of these devices, so make sure you download the correct one.
For the time being, Android 4.2 Jelly Bean factory images are available for Nexus 4, Nexus 7 3G and Nexus 7 Wi-Fi nakasi, as well as Galaxy Nexus GSM takju.
Android users who own other versions of these Nexus devices will have to wait a bit longer for Google to release the factory images for their devices. Stay tuned for more updates on the matter.