Demon smiter (trait) action

[Salubri]

What action does it take to use the +4 trait bonus? A standard action seems like to much (why not just cast true strike for +20)

Benefit: Once per day when fighting demons, you gain a +4 trait bonus on a single attack roll.

[Trekkie90909]

I would assume you just have to declare you're using it before the attack roll is made.