The time between detection and the CME hitting us would probably be measured in minutes. I don’t think it’s possible to shut down the grid in that timeframe.
In https://en.wikipedia.org/wiki/Carrington_Event it is estimated that the time from spotting the flare to the solar storm was 17.6 hours. That's plenty of time.
The problem is figuring out how big the event is, and how directly it will hit us. So while we have over 17 hours to prepare, there might be some false positives due to our limited prediction skills. And, no matter the real consequences, people have limited patience for large economic disruptions over things that turned out to be nothing.
There's no reward for fixing a problem that doesn't happen and that people don't want to believe even exists. Bonus, if other networks are damaged while yours aren't, it must be because you protected your network so you're responsible!
So the information chain, starting with the telescope that detects the flare, and then has to work it's way up the food chain, so that sufficient people agree, and take presumably synchronised action, well, good luck with that.
You'd also ideally need a multi-hour warning, planes gotta land etc.
Make no mistake, shutting it down will result in some deaths [1]. And those deaths will be on the news tomorrow (if indeed news still exists.) On the other hand not shutting down will cause more deaths and massive destruction.
[1] think hospitals where the backup power failed, or didn't last long enough. Traffic intersections. Elevators. Water pumps. Airplanes. Trains. Take your pick.
Let’s ask the photon how much time has passed between it being created and hitting our eyeballs. I’m sure it will produce a very sensible answer—oh dear, hmm…
The problem is communicating to everyone when that 8 minutes starts and how much time is left.
It is something we computed. Why? Because there is no way to measure the time it takes for light to get from the sun to the earth. You cannot synchronize a message. There is no "hello". There is no beginning. This is not like firing a starting pistol. We cannot ever know what is happening at the sun with less than 8 minutes of lag. It is a fundamental limit. Even sending a highly robust and extremely precise clock into the sun to measure events, then comparing those events to timelines on earth, would not work. You cannot do it in real time, but even after the fact is pretty much not possible due to relativistic effects.
This has been done with the moon.
But your points about no 8 minutes of warning stand.
That's not how it works. There may be detectable precursors that could actually give warning, but the 8 minutes referenced is the time it takes light from the sun to reach earth. It's immediate in the sense that it is physically impossible to detect that before those 8 minutes have already elapsed and the light is hitting your detectors. You could try to move your detectors closer to the sun to detect earlier, but any signal you can possibly send back to earth goes at the same speed, so it doesn't help.
So maybe we are able to detect that at time X there will be solar flares. We know they will be here at X + 8min.
But if we start moving away now from the sun, we will have more time to deal with it.
If it was immediate it should also be immediate even if we moved to 20x distance of the sun, or no?
But we're not worried about that part of things anyway - it's the mass part of the CME that is the issue.
Take the 2003 blackout. Yes, the whole shut down took 15 minutes (?). But thats because it was a cascading effect that had to travel down the lines. Once the fault was detected by a particular segment of the grid, the relays responded in milliseconds. They have since the 1920s? Add in an "incoming solar flare" fault condition and we can trip the whole grid in seconds and send a start signal to the diesel generators to warm up to bring her back up.
Pretty nifty trick.
Question is why would we? The grid has been undergoing a lot of strengthening against EMPs and flares for decades. Its not obvious to me that a flare can take it out, especially if we shed dumb loads (partial blackout, say data centers) before it hits to give the conductors and transformers head space.
Geomagnetically-induced current is different from the plain-vanilla EMPs anyway—GIC can last for hours.
If stuff was shielded, isolated, and grounded better, everything from your phone to your WiFi would work a lot better and have longer range. Wind slapping power lines together wouldn't destroy everything plugged in inside your house and solar flares wouldn't be more than a passing concern. The design changes to affect all of this aren't remotely expensive or difficult, we just don't.
Would this also affect m mammals, including us then?
Speaking from personal experience, this is BS. During a bad wind event, a bunch of lines came down, started a huge forest fire around 10 or 11pm which was heading for a small town with 50-70mph winds. First responders couldn't get in to warn anyone because the downed lines were energized, so they called up the power plant. The whole process to de-energize took hours. There is a kill-switch now, but most power plants apparently can't shut off the juice in a matter of seconds, and they may not even have a plan to do so in an emergency.
But even if is, it's going to kill and hurt a lot of people. Probably less than setting every electrical device on (half of) the planet on fire or whatever, but good luck convincing people of that when their dad is on dialysis or all their food spoils and they can't get to the store.