When you're in the same room as the officer? In the same line at McDonald's? Only when in direct conversation?
"Excuse me sir, your fly is open. Oh by the way, now that I'm talking to you I am required by law to inform you (and raise your adrenaline level) I am carrying a concealed firearm". Hmm, I fail to see any good side to this. In practice, do CCW holders really make such disclosures even in casual interactions?