At TenacIT we have an internal process for change management which is a little more rigorous than our clients are willing to tolerate on their own systems, simply from a cost perspective.  What we provide for our clients is a list of services that need to be performed.  The details of what changes will occur, duration of downtime (if any), users affected, and fail back process are included.  Those changes, if approved, will be conducted when it is best suited for our client unless an emergency requires immediate action.