BiCon 2015's bookings have just passed the 200 mark with 11 weeks to go. Rah rah them, etc.
But it does take me back to the first time I ran a BiCon, in 2000. When we hit the 200 mark, which in round numbers was about a month out, we had to drop the remaining publicity plans on account of having no additional capacity at the venue we could expand into. The final tally of 265 attendees was fab, but with the frustration of knowing it could have been more like 350 if the rest of the planning grid had worked out.
Sometimes you just get lucky with your venue and who else wants to be there that week :)