According to a number of tips we've received (mostly from India), the anticipated upgrade for those who remain on legacy hardware is available should official support channels be unavailable. Users can simply bring in their phone and have them updated right there by Nokia, even before the "early 2013" date.
The new OS is currently resting on Nokia's servers, and is confirmed to be available for the Lumia 900, 800, 710 and 510. It's advised that consumers contact their local Nokia Care centres to see if the 7.8 update is available for your Lumia Windows Phone (you can start by drilling down through Nokia Support).
We previously looked at Nokia and Microsoft rolling out the Windows Phone 7.8 update, which later turned out to be limited to just pre-production devices only. We're still impatiently awaiting the notifications to begin trickling through, but at least there are channels for consumers to manually upgrade hardware.