1) The CCA BOD and other interested club members are also dealers or at least have tables on the bourse floor at the convention which they typically cannot be away from for very long during the day.
2) Need to make sure there is adequate time to deal with any business during the meeting. If it started at 8:00 AM then there would only be one hour to deal with club business.
3) The convention is a time when most if not all of the CCA BOD and other interested parties are physically in the same place.

Cheers!