Strangely, the Christus Rex Society suggests beginning one's Novena to Christ the King on Saturday the 17th, to conclude on Sunday the 25th, Feast of Christ the King - when surely it should begin on the Friday (the 16th), and conclude on the day before the Feast.
After all, Our Lady and the Apostles made the first and greatest Novena, or nine days' prayer, between Ascension and Pentecost - that is, from Friday after Ascension until Saturday, the Vigil of Pentecost. The nine days' prayer finished, God the Father having resolved from all eternity to answer the plea of His Saints made through Christ, and so fulfil His Divine triumphant Son's promise, God the Holy Ghost came down...
A novena, therefore, is best made for the nine days before the prepared-for day: it is, after all, a preparation. However, to exclude all superstition, there is nothing magical about the number nine, however fitting it is to imitate that first nine days' prayer in the Cenacle; what is called for is persevering prayer, with one mind and heart in God, that His will be done.
In any case, here is the suggested Novena Prayer, which attentive readers will find to be taken from the "Jesus King of All Nations" private devotion, with the pronouns archaized (see here for the original):
NOVENA TO CHRIST THE KING
Recite one Our Father, one Hail Mary and one Glory Be per day followed by the Novena Prayer:
O Lord our God, Thou alone are [sic; lege art] the Most Holy King and Ruler of all nations.
We pray to Thee, Lord, in the great expectation of receiving from Thee, O Divine King, mercy, peace, justice and all good things.
Protect, O Lord our King, our families and the land of our birth.
Guard us, we pray, Most Faithful One.
Protect us from our enemies and from Thy Just Judg[e]ment.
Forgive us, O Sovereign King, our sins against Thee.
Jesus, Thou art a King of Mercy.
We have deserved Thy Just Judg[e]ment.
Have mercy on us, Lord, and forgive us.
We trust in Thy Great Mercy.
O most awe-inspiring King, we bow before Thee and pray;
May Thy Reign, Thy Kingdom, be recognized on earth.
It amuses me - hopefully not too impiously - to find Traditionalists using such a modern prayer from American visionaries of the 1980's and '90's, while my old Opus Dei prayerbook (Socías, ed., Handbook of Prayers) contains, in Latin and English, an impeccably "liturgical" devotion to Christus Rex, one that involves Psalm 2 (in the Neo-Vulgate) with the second antiphon (from Daniel vii, 27b) of the Vespers and the old, pre-Vatican II Collect of Christ the King: surely this is a preferable form? This alternative runs thus, but substituting the more familiar and Traditional Clementine Vulgate ("O my darlin', O my darlin', O my darlin' Clementine..."):
PSALM 2Aña. Regnum ejus regnum sempiternum est, et omnes reges servient ei et obœdient.Quare fremuerunt gentes, * et populi meditati sunt inania?Astiterunt reges terræ, et principes convenerunt in unum * adversus Dominum, et adversus Christum ejus.Dirumpamus vincula eorum: * et projiciamus a nobis jugum ipsorum.Qui habitat in cælis, irridebit eos: * et Dominus subsannabit eos.Tunc loquetur ad eos in ira sua: * et in furore suo conturbabit eos.Ego autem constitutus sum Rex ab eo super Sion montem sanctum ejus, * prædicans præceptum ejus.Dominus dixit ad me: * Filius meus es tu, ego hodie genui te.Postula a me, et dabo tibi gentes hæreditatem tuam, * et possessionem tuam terminos terræ.Reges eos in virga ferrea, * et tamquam vas figuli confringes eos.Et nunc, reges, intelligite: * erudimini, qui judicatis terram.Servite Domino in timore: * et exsultate ei cum tremore.Apprehendite disciplinam, nequando irascatur Dominus, * et pereatis de via justa.Cum exarserit in brevi ira ejus, * beati omnes qui confidunt in eo.Gloria Patri...Aña. Regnum ejus regnum sempiternum est, et omnes reges servient ei et obœdient.V/. Domine, exaudi orationem meam.R/. Et clamor meus ad te veniat.Oremus.Omnipotens sempiterne Deus, qui in dilecto Filio tuo, universorum Rege, omnia instaurare voluisti: concede propitius, ut cunctæ familiæ Gentium, peccati vulnere disgregatæ, ejus suavissimo subdantur imperio: Qui tecum vivit et regnat in unitate Spiritus Sancti, Deus, per omnia sæcula sæculorum. R/. Amen.
I wonder which Novena prayer I'll use?