Delayed Flights Can Leave Prior to Posted Time!
Two days ago, I arrived at SLC to find my connecting flight to Long Beach delayed by one hour. Scheduled 8:22pm moved to 9:22. The airport monitors, the Delta app, and my cell phone alert all gave the same time.
Relaxing at the Skyclub, at 8:35, I noticed the monitor now showed 8:52. So did the Delta app. I walked briskly to the gate to find first-class boarding. Pushed around 9:05. No announcement at the Skyclub. I have no idea if the GA did anything to find stragglers, if there were any.
Lesson: Don't be surprised if "delayed time" suddenly advances.