I'm a somewhat professional predictioner.
It's a joke, but still.
Judging from the way they posted about 7.1.5, 7.1, pre-downloads, readiness and all, I would say...
~2 weeks? Stretching it is max 3 weeks.
If we get lucky, we get it on this 28th, a long shot.
They usually start the previews about a month before release, well, the more "specific ones", for almost every patch they've done this, because it makes sense.
Updates to probably come with this week's Developer stream.
28th or 4th are prime candidates, they wouldn't announce the pvp season ending "soon" and then stretch it out for 1.5-2+ months
28th, with the Q&A for 7.2 this week its for sure.