Pick a day that suits you, cause you haven't even been able to race. You can't pick a day that will suit everyone, so just pick a day and people will come if they can.
Dumping the last person from the event is kind of pointless. What is the idea of doing that and what if its you?
Get a backup race director/admin to run the event if you can't make it. People will not race if you keep cancelling the event.
Don't over complicate things. Don't try to do to much. You have a simple idea, let it run for a bit before expanding cause you might dilute things too much.