The perfect plan would be to nuke your enemy such that your warheads land about 10 minutes before the cosmic event. Any retaliation by your enemy would be muted by the event, and then they would be back in the Stone Age.
Don’t put that plan past North Korea, etc.
just saying.
Nope--that's too early. They will see the nukes coming, and launch themselves. Given the electronic nature of nukes, there is no "good" time to launch without getting nuked yourself.