Usually we do not see a new build on a weekend. The announcement was only a few days ago am certain that just like other builds they have to evaluate the them for release. Also there will be prep needed to help transition those who want the build. Strongly recommend reading the build notes completely before pressing that download button. That way if you need to adjust something on your system to prepare it wont be as complicated a process.
Have read different comments about release. It will happen this week. Normally the releases are not out on a monday but anything is possible. This is a new version of Windows and not recommended for your daily driver machine.
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If you need ISO to recover install existing build you can go to Flight Hub to find the ISO.