Place it at the exact frame you declare riichi, then follow it with Anime Ahh for your opponents' response, and save JoJo To Be Continued for the cliffhanger before the winning tile is revealed.
About this sound
This under-a-second voice clip from Mahjong Soul has Ichihime announcing riichi with a bright, cat-like nya at the end. It feels playful and triumphant, like a cute victory call in the middle of a tense hand. The line comes from that mahjong game, where Ichihime is one of the playable characters who calls riichi during a match.