You could add a small digital clock for the streamer to enable or disable. This clock could show the viewer, the streamer's local time. So when the streamer says they will be back online at 7pm. We can tell how many hours that is for them and then for us. You could also put the viewer's local time there too so you can even tell how far apart the times are. We watch too many streamers from all over the world to keep track of their time zones.