Understanding Office 365 ProPlus Updates for IT Pros (CDN vs SCCM)

aarony Let me start with the easy one, Office 2019 behavior is the same.  As you stated, M365 Apps and Office 2019 use same code base so same behavior.  By design, SCCM uses some internal randomization in terms of timing, there are a bunch of timers at play. (this is the reason precise timers are not provided as they will be different by design)  To my recollection, when I did testing for this scenario, I had to be patient and wait for SCCM to do its thing and stage the content on the machine.  Once that happens, the next launch of Office application will result in the "BusBar", the yellow banner in app notification saying updates are pending and user can drive change.  If an Office application was already open it won't show the BusBar unless you close and reopen it.  Therefore, the greater window prior to deadline would give users more time to drive the update themselves before deadline.