First contact is not one event.
First contact can be a radio signal, a verified craft, a biological presence, an autonomous probe, a public announcement, or a direct local encounter. The public imagines a world leader walking to a microphone. The more useful question is uglier: what if the first confirmed moment happens near people who have never rehearsed it?
That is the civilian first contact problem. Governments can debate. Scientists can verify. Newsrooms can publish. None of that helps the person standing closest to the anomaly when the room loses its mind.