Place it at the exact moment of the reveal, after the setup and just before the reaction shot, then follow it with the game show buzzer for a wrong guess or the bruh sound when the guess leaves everyone stunned.
About this sound
The Mentalista clip is a brief voice meme sound built around the idea of a mentalist, someone who seems to read minds and predict what others are thinking. It gives a playful, knowing feeling, like a joke has just clicked and the guess was far too accurate to be chance. Editors use it as a quick cue that a character has worked something out.