Depends on the lacquer, how thick the coating is, and the atmospheric conditions (temp, humidity) It can take anywhere from fifteen minutes to several hours. The term fully is not easy to define, either. It is one of those Zeno's paradox things. The outgassing is one of those exponential decay functions that approach zero but never quite get there. It will outgas some for days, but you do not need to wait that long. If you are trying a new lacquer, or for any reason worry about it, spray or brush a test piece when you do the model, and try your next operation on it when it feels dry.
With fast drying lacquers, watch painting in very high humidity. It may blush. This is a situation where the rapid evaporation significantly cools the surface below the dewpoint, and water condenses on the surface. This creates a whitish, slightly rough surface that looks terrible.