The Feast of the Nativity of St John the Baptist not only has a Vigil, but a Common Octave! Amazingly the Vigil was kept in the 1962 Missal, but the Octave was not. The Octave is June 24 - July 1. Originally the feast of the Most Precious Blood was celebrated on the 1st Sunday in July, but Pope St. Pius X moved it to July 1. Hence the Octave day of SJB is the Most Precious Blood of Jesus.
Every yeat this Octave overlaps with the Common Octave of the Feast of Sts. Peter and Paul
which is July 29 - July 6.
