legwandfly - three days a week, 12p to 4p!
It must have been pure dumb luck and persistence I was able to go from Application Submitted to Approval Notification in 17 days. My officer said cancellations were pretty frequent, and that often times, she would receive calls to cancel, which she had to hand-process (versus the schedulee popping over the the GOES site and cancelling themselves.) Those cancels would show up as openings within 24 hours, versus almost instantaneously when handled by the site.
All of which is to say for anyone checking this thread, keep hitting the schedule site back once you've got one on the books because slots open at your preferred location all the time.