Earlier today, Microsoft announced a number of new gaming features that are coming to Windows 10 in the Creators Update, saying that Insiders will see them in a new build tomorrow. As it turns out, this will not be the case, as Larry Hryb (Major Nelson) has confirmed that the build will roll out later this week.
Since tomorrow is already Thursday, that would mean that Friday is the likely day that we'll see the new build, which was reported earlier today to be 15019. Of course, at this late of a stage in the development cycle, Saturday isn't entirely off of the table either.
Naturally, the build number is subject to change as well. 15019 should be treated as a rumor for now, especially as it continues to be delayed.
The original blog post has been changed from "today" to "this week", which means that Xbox Insiders shouldn't expect a new build tomorrow either. There weren't to be too many new features in it anyway, with things like built-in Beam streaming promised for a later date.