I somehow missed this thread..
You should wait for the CEL to off, so that is has time to run self-checks and let fule pump prime iteself..
Why should you let the fuel pump prime itself? Becaus it brings the injectors to full pressure before cranking.
The car will fire (in most cases), regardless of if you wait or not.. But if you do wait, your mechanical components are following they're normal cylce. Otherwise, it amounts to a slight shock/ "trauma", every time..
