Year 31 BC was either a common year starting on Tuesday , Wednesday or Thursday or a leap year starting on Tuesday or Wednesday ( link will display the full calendar ) of the Julian calendar ( the sources differ , see leap year error for further information ) and a common year starting on Tuesday of the Proleptic Julian calendar .
Year 31 BC was either a common year starting on Tuesday , Wednesday or Thursday or a leap year starting on Tuesday or Wednesday of the Julian calendar .