In OSD and ROSA, when an upgrade is scheduled following the documentation [1] [2], the upgrade may last some time to start (in some cases, it could be more than one hour).

4.10+

There are three time here:
The time when customers create the scheduled upgrade policy
The time customers created the upgrade policy when should the policy start.
The time when the policy really start.
So I suggest, "The upgrade starting time maybe later than the scheduled time. It could be sometimes an hour or longer."

Correctly specifying the information in the note. 

A note mentioning about the delay in the start of the scheduled upgrade.

OCPBUG-10383