They didn't revealed release date, we always get estimated season on pre-order page (for example Legion/BfA before 23rd September, SL/DF before 31st December). But pre-order happened so late (9 months later than Shadowlands!) and December is pretty much out of question for release, so 15th or 22nd November release is almost certain...
... if they will be ready of course. Yes, historical data is against it, Alpha/Beta have to be concluded in 4-4.5 month. But here's the thing - it's not like deadline was revealed year ago (like with Warcraft 3 or SL) and we had no Alpha since then. We got this date NOW, almost right before Alpha. So I'm more in curiosity than panic mode.
We will see if Alpha is more advanced than usual. Key thing will be talents, I think no matter what they will release zone per build anyway to focus all feedback on single thing.