I probably oversimplified quite a bit. There are two main probes that I know of that sit between us and the sun. The alert will happen and then things get noisy in the ionosphere - I’ve never actually sat with a stopwatch, but I’m curious so I’m going to do it next time. Flares aren’t binary - their magnitude starts off low, peaks and then ebbs. I and not sure at what point in that flow do they send an alert, and at what point in the flow do I notice things on my end.