Back when I worked at a major cloud provider (which admittedly was >5 years ago), our alarms would go off after ~3-15 minutes of degraded functionality (depending on the sensitivity settings of that specific alarm). At that point the on call gets paged in to investigate and validates that the issue is real (and not trivially correctable). There was also automatic escalation if the on call doesn't acknowledge the issue after 15 minutes.
If so, a manager gets paged in to coordinate the response, and if the manager considers the outage to be serious (or to affect a key customer), a director or above gets paged in. The director/VP has the ultimate say about posting an outage, but they in parallel consult the PR/comms team to consult on the wording/severity of the notification, any partnership managers for key affected clients, and legal re any contractual requirements the outage may be breaching...
So in a best-case scenario you'd have 3 minutes (for a fast alarm to raise) plus ~5 minutes for the on call to engage, plus ~10 minutes of initial investigation, plus ~20 minutes of escalations and discussions... all before anyone with permission to edit the status page can go ahead and do so