Dan, I think I've got it. The evening starts out at 6 PM with a concert, followed by 2 & 3 at the same place, and then shifts to another nearby place for 4.

Is it reasonable to assume that Open Sing begins about 9 PM? Is Open Sing more of a free-for-all assertive format, mechanical take-your-turn, or does it vary by the evening? Are instruments welcome or particular ones forbidden? Are there typically a lot of non-singers there? It sounds like it could be fun for newcomers but, you know, this is NYC and I'm not sure what assumptions should be made.