Thanks for the heads up! "Starts soon" usually means in the next 1-3 days. It would be interesting if this event was made to overlap with the current Rescuer event, as usually events don't overlap. But, that could just be a side effect of pre-planned Gunner Golden Son timing overlapping with the delayed Rescuer timing.
In any case, it makes me think we might see the LoL dungeons stay open on Thur and Fri, which would also help those farming LoL for Regular Souls for the Rescuer event (unless the Golden Son event begins today).
In terms of the character choice, he stays in line with the pattern I noted in my first post. I like him quite a bit and actually have two at 5*. I'll try to get 2-3 from the event for the Altar. As explained in a recent excellent post by Amarthir, these events are some of the most efficient ways to hit high-level Sacrifice Tiers for a chance at other Souls and Skill Shards.
Also, if the pattern holds for the Assassin, that would mean we'll see Corrupt Rescuer, Artillery Dog, or Corrupt Harpy.