I was looking through the historical betas, and I see that there were always at least 7 days between betas. Does that mean that, for instance, Computer Science Educators won't appear for five more days, even though it made it to 100% complete shortly after bioinformatics?
Sites launch on Tuesdays. There is not, to my knowledge, an authoritative explanation of why it's Tuesday. But it's apparent that Stack Exchange activity is lower on weekends, which is not good for getting a site started. So launching early in a week makes sense. On the other hand, Mondays are hard enough without having to launch a new thing.
So CS Educators will wait for this coming Tuesday, or the Tuesday after that should anything delay its launch.
The Tuesday schedule still leaves a possibility of launching two sites on the same Tuesday. And this happened a few times in the past:
- History of Science and Mathematics and Home Automation both went into private beta on 2014-10-28.
- Arabic Language and Portuguese Language both went into private beta on 2015-10-14.
But it never happened that both sites launched on the same day survived. In the above examples, Home Automation and Arabic Language have been closed.