In fact, John Mueller thinks it might not be fully live until later this year. He said it is definitely not launching in a week or so but Google currently does not have a date for when it is going live.
He said this at the 51 minute mark into this mornings hangout when Dawn asked him how soon until it is out.
John said, "I don’t have any dates." He added, "I would guess, later this year sometime."
I don’t have any dates.
It is not going to be years. I would guess, later this year sometime. But we will inform people as we get closer, as we have a date, so there is sufficient time for people to resolve issues that they might need to resolve.
We will try to also inform sites where we recognize issues. Such as maybe your mobile version doesn’t have all the same content and markup that your desktop version has. And we will try to let you know of that through Search Console as well. So that you are kind of aware of these issues.
I don’t know about Q1 but it is differently not like next week where we will be switching it on.
Here is the video embed so you can watch it yourself:
So no need to panic yet - we should have plenty of warning from Google before it goes live.
Forum discussion at YouTube.