I remember the destroyer sound effect being brought up in discussion when SirRidley was working on the sound/music for this scene and there were a few attempts at making this change. Unfortunately none of them felt entirely seamless and so the idea was dropped from the final edit.
Yeah. There isn’t really a natural place for the sound effect. If you place it early and Finn doesn’t react until later it wouldn’t have the impact needed. If you place it just before Finn reacts I think his reaction still doesn’t match, a sudden sound should lead to a quick reaction. And if the sound is what they react to there’s still the question of how everyone got out to look so soon. I think a sequence where the sound could work would need a new shot, perhaps a shot like in TLJ where the Star Destroyer appears above Takodana (which would explain what the sound is, that would be unclear for first time viewers) or perhaps an interior shot of people in the bar hearing a loud bang outside and going out to see what’s going on, followed by the sequence as it is or maybe with the crowd shot moved before the shot of Finn.