Place it at the exact frame the fake message pops up, early in the edit before the reaction lands. Follow it with a game show buzzer for a wrong-answer twist, or keep it solo before a cut to the confused face.
About this sound
This is a 1.3-second bass boosted version of the Samsung notification tone, with the familiar alert pushed into a deep, heavy hit. It feels funny and startling at once, like an ordinary message suddenly acting dramatic and overimportant. It comes from the standard Samsung phone notification sound, re-edited for meme use.