Unfortunately the way Sonos works means there’s a delay between “starting” audio playing and the actual sound coming from the speakers. This buffer allows synchronised music from multiple rooms/speakers. When the source is tv audio the delay to the soundbar is minimised (30msec or so) to try to eliminate lip-sync issues, but the delay to other speakers is still the same (70msec or thereabouts). In your configuration this will result in a terrible echo effect. For music though, all will be fine. You could, I think, use the ceiling speakers as surrounds though, as a different setup. Music streaming will be synchronised too in this setup.