I could be wrong, but I don't think anyone on a potential steering committee has any extra time for an additional meeting. I think you would want to have it during your meeting time.
Typically, what we did when I was a chair was have our two scheduled meetings, and maybe once every sixth or seventh meeting or whenever, we would have a steering committee meeting. This would mean that nobody else came; it would be just the steering committee members who would be at that particular meeting and make decisions.
It's not an extra meeting.