Place it right after the command in a gameplay edit, as the character's reply, then follow it with Okay Let's Go to send him off to work. If that job turns into a fight, cut to Enemy Spotted when he reaches the scene.
About this sound
Oui messire is a French reply from the Human Peasant worker in Warcraft 3, spoken when the player gives him an order. It lasts about a second, in a clear, ready voice that sounds too pleased to obey. It feels funny, turning yes sir into a joke about cheerful, unquestioning service. It comes from Warcraft III: Reign of Chaos, the 2002 Blizzard strategy game, in its French version.