I think we can put various clues to gather and explain why the attack suddenly occurred.
1) There were negotiations between Iran and the US which the
Omani chairman thought were just about to get somewhere.
2) The iranian senior leadership got together, potentially to sign off a deal
3) The last thing israel would want is for a deal between Iran and the US to be done
4) Israel had intelligence that the Iranian senior leadership were coming together to sign off on a deal, and the Ayatollah was at home with his family.
5) The Israelis tell the US they are going to take out the Iranian senior leadership (and having watched St Trinians some very dangerous Iranian school girls). Unless the US takes out Iranian ballistic missile systems ,without senior leadership in place, they'll default to attack the US.
6) The US scrambles to take out the missile systems the Israelis have told them are aimed at US facilities before / at the same time as the Israeli decapitation of the Iranian leadership and highly dangerous school girls.
7) US then thinks about consequences, shipping, evacuation, etc.