The Feast of the Sacred Head that was proposed by Teresa Higginson falls on the octave day of the Feast of the Sacred Heart, that is the Friday after that feast. She was to state in a letter to Fr. Powell on June 2nd 1880:
“As I told you, our dear B. Lord expressly asked me to tell you from Him that He wished His most Sacred Head to be publicly worshipped and honoured as the Seat of Divine Wisdom, and said too that the Friday, octave day of the feast of the Sacred Heart, should be dedicated as a festival day in its honour, and special reparation and atonement be then offered to Him.
For He said, ‘See oh my beloved daughter, I am clothed and mocked as a fool m the house of my friends; I am crowned in derision, I who am the God of Wisdom and all Knowledge, I the King of Kings, the Almighty and All-powerful One am presented with a sham sceptre, and if thou wouldst make some return, thou canst not do better than tell my servant E. from me that I now wish the Devotion made known which I have so often communicated to you, and I wish the first Friday after the feast of my Sacred Heart to be set apart as a festive day in honour of my Sacred Head as the Seat of Divine Wisdom, and that public adoration be offered to Me for all the outrages and sins which are continually being committed against Me.’
He also said that you must not be disheartened at difficulties that may and will arise and crosses that will be numerous. He will be your support and your reward is great. ‘And anyone who shall assist in furthering this Devotion shall be blessed a thousand fold, but woe to him that shall reject or go against my wish in this respect, for they shall be scattered in my wrath and shall know their place no more, but to them that honour Me I will give of my might, and I will be their God and they shall be my children and I will place my sign upon their foreheads and my seal upon their lips.”
The Sacred Head devotion was intended to be the crowning of all devotions, and the completion of the one of Sacred Heart, as the Sacred Head, seat of Divine Wisdom, governs the motions of the Sacred Heart. Hence it is a feast that completes the Sacred Heart Octave, and is the final one that is determined by Easter, and the completion of the liturgical cycle of the Paschal mystery. In many respects it is similar to the Feast of the Divine Mercy, that falls on Low Sunday after Easter, and which is at the end of the Easter Octave. The Divine Mercy Feast is the first to be determined by Easter, and the Sacred Head the last. And likewise both spring from the great fount of Mercy the Sacred Heart, pierced by the lance from which flowed blood and water.
The Feast and Octave of the Sacred Heart is a fairly recent addition to the calender: the liturgical propers of the mass and the office were compiled by St. Jean Eudes in around 1670, and feast only became celebrated in the universal church in 1856 by decree of Blessed Pope Pius IX. Unfortunately the Octave of the Sacred Heart was abolished by Pius XII in the pre - Vatican II reforms of 1955 of the missal and breviary. And for the Feast of the Sacred Head, there are still no official mass and divine office propers that can be used, as the church does not officially recognise the feast at present. Hence the faithful currently can only celebrate it in a private capacity. However in the future this will change, please God!