Lol - they are twins, does that count as psychic? ;)
Seriously though, Allard gave them the order to be ready at their stations ("Keep the lights on") to fire before anyone engaged in combat and gave the target ("Masked karker!") before he was pulled. So they'd be ready and have the target by the time Allard was coming out of his roll forward to fire.
The second cannon shot I could see being no issue as it would come after the rest of the attacks.
I mean, the ship only recently landed into what it knew to be hostile territory as it was a slaver camp they just attacked. But alright, I'll concede the point on that