Whatever you do, DON'T leave the immediate area of the loading table with loaded guns! That's gonna cost ya ....
As for not being ready, why not? Most shoots organize a possee rotation and if it's your time to shoot - shoot. You've had a shoot copy, a walk-thru and the same time for prep as anyone else. Unless you've been busy working elsewhere, you're asking for special consideration.
A brain fade on your part does not constitute a crisis on my part, and it isn't fair to the guy behind you who has to step to the line while you get your ducks in a row.
It's a game based on a gun fight scenario, as fanciful as we want it to be. You don't rehearse gunfights, they just happen. I came to CAS from IPSC shortly after I got out of Regular Army. I regarded shooting as a martial art form. At a CAS match I got into a shoot-out tie with a guy and as I approached the stage, he was busy pacing off his steps to his staged shotgun, picking it up and pointing it through the window, etc.
The RO arrived and I told him to fuggedaboudit, letting the guy win by default. Had he elected to shoot the scenario 'cold' as I intended, it would have been a true contest. I think they got the message and he got a hollow victory.
That's when I started to dislike gamers and gamesmanship, something I thought I'd left behind in IPSC.