1. 1. Set it up. Name the event, pick how long it runs, and mark when you are free.
2. 2. Share the room. Everyone fills in the same thing, in their own timezone.
3. 3. Get an answer. The earliest window that fits everyone, or exactly who is blocking it.

Rooms delete themselves 7 days after they are created, however far out the event is — save the calendar entry and the time is yours. No accounts, no email, no reminders.