Many days pass before release notes are posted. (I'm pretty sure I've recently seen instances where they weren't published before the next release!) They should be posted simultaneously with the software update release, if not before. When there's a new release, the software behaves differently. Whether it's a feature improvement, bug fix, or a newly introduced bug, it affects your users. Rather than leave us (and likely your support staff too) in the dark and have everyone confused why something isn't working like it was before, please issue the release notes simultaneously, if not before, the software update is released.