eleven o'clock
`` The only suggestion I have to make is that we rotate the hours , if we keep this up many nights . '' `` What do you mean ? '' inquired Fred . `` Why the one that comes on at eleven o'clock one night comes on at twelve-thirty the next night . The one who comes on at twelve-thirty will report at two and so on . We 'll just keep pushing the schedule up every night so we 'll all be the same when we 're done . '' `` How shall we know when our turns come ? ''