If its instant it sounds like it receives just one pulse. VS plugging an Event Tick into add actor world offset and setting an offset. But then that depends if it is a character or pawn or just an actor bp.
IF you used the event tick then the “speed” should be how much offset you are apllying X Y or Z.
My shipscroller thread has some simple logic how to get smooth movement with a set actor location SHIPSCROLLER (Side) - General Movement Theory - Programming & Scripting / Blueprint - Epic Developer Community Forums props to @ClockworkOcean for helping me figure that one out.