The backorder email Google sent people said it would be an (up to) 3 week wait to fill existing orders.
If we factor in the original launch of Nov 13, the earliest I would expect to see it on sale is Dec 4
But as far as I know, no reliable resources
Yeah just like TgD said, the only info we have so far is from Google - "up to 3 weeks" for the people who managed to fit in an order on launch day. We don't know how many they sold that day, but knowing how many tech savvy people weren't able to get one gives you an idea of how quickly the next batch will sell too.