Is this possible? I have been wondering this since I am working out a quest and I want to activate an encounter trigger when the player is at a certain quest state.
See https://nwnlexicon.com/index.php?title=SetEncounterActive
You could flag the encounter as inactive in the toolset, active when the quest point is reached.
You already know how to determine quest state via script, so you can give the encounter an OnEnter handler which will make it active via SetEncounterActive. It will then immediately spawn its creatures as if it was always active.