Thank you AaronD.I don't think that's possible. @Warmuptill can give a better answer on that than I can, but it requires the server end to support that too (YouTube, Facebook, Twitch, wherever you stream to), not just Adv. SS. If the server doesn't support doing that automatically, then it must be manual. I remember when YouTube had a much better remote control API than it does now, and they killed it to get rid of spambots...
What you might do though, is not create a separate broadcast every time, but reuse the default one. That's what I do. You lose the automatic announcement to your audience that you're going to stream at <this time>, but my audience knows the schedule anyway and doesn't need that.
I also stream about 15 minutes of "leader" before the actual start time as I see it, just for people to find it and see that their end works. Some sort of changing graphic that includes the actual start time, and some sort of sound. And about 10 minutes of "trailer" (silent still image), to let them leave on their own before getting kicked off.
Anyway, I just start throwing data at it, and the stream starts. Stop the data, and YouTube times out and resets, ready for the next one. Easy as that. Same key. And I do use the stream key; OBS is *not* logged into my account.
It always shows up when I am not logged in. I need to be logged in and having the stream key entered so it disappears.
Now I am trying to run a couple of overlapping Youtube streams on a channel and schedule that with AdvSS. I am trying a couple of profiles each runs on a separate instance of OBS. One isn't asking for the broadcast set up as I am logged in and got the stream key set, but the other keeps asking for it.