I don't have any other information than the dev blog about Rejuv's dev pace, but I don't think V13 can be coming before at least three months. I'm saying '"three" because I really don't want to be wrong, seeing as how dev started last August and the progress bar isn't half done yet (of course there's been unexpected stuff, progression isn't linear, they had to wait for Gen 8, Jan's been ill, and so on).
You very likely will not get any estimate for the release date from the dev team, because it's hard to predict and quite a bit is unexpected.
(and if you actually got one, well, it would probably be so visible that you wouldn't need to ask the question).
Arminius glares ahead for a moment before letting his shoulders slump. "Not much. Your brother has another... well, I hesitate to call it a trap... but you know what I mean. Anyway, he's up there with something for us to do, right?"