Electrician should be able to make holes without having to touch up anything. If they can't cut proper holes in plaster ceiling, or line up everything without marking on the ceiling, you have a lousy electrician.

The plaster ceiling fellow only has to make sure to install the fan hooks and pull the wire through the ceiling for the electrician. Make sure enough of the fan hook is protruding and the wire is below the ceiling level, otherwise the electrician will probably have to cut the ceiling which will require touch up.