To further demonstrate your authority, prophesy is essential. It is easiest to adopt an established prophetic text and offer a new interpretation in which its amorphous rhetoric predicts your cult in explicit, lucid terms. The books of Nostradamus, Cayce, Blavatsky, Revelation, Daniel, and Ezekiel are the most common, but the same applies to Liber al vel Legis, the Eddas, the Upanishads, the Bhagavad Gita, the Cabbala, or the Book of Coming Forth by Day. The text must to used to show that coming events fit into the context of a larger scheme that has been all planned out. Systems of astrology, numerology, or other divination can be absorbed to give further credence to predictions.
As the interpreter of the prophesies, the Charismatic Leader embodies the spirit of knowledge itself. He must explain every ongoing event as it fits into whatever overarching scheme he has imposed upon the world. It is his responsibility to fudge any incongruities or failed predictions. Most of this is practical psychology and will be learned in time with experience. The Leader should enhance his power and influence by showing how he "predicted" events in the past which have already happened (or convincing people he has) or by making prophesies so ambiguous that they can be attributed to the next newsworthy event. Skim Revelation and Nostradamus for examples. Predictions must always be hopelessly vague, e.g. "The nation of nobility will suffer hardship, the economy will rise before falling again; technology will create a monster that devours the fruit of labor."
Exact date-setting should generally be avoided (unless you have the means to successfully reify your prediction) but a Great Disappointment doesn’t signify the end of a movement -- fast excuses can always be made and community bonds are always strengthened by hardship. The Watchtower Society (Jehovah’s Witnesses) forecasted the End in 1914, 1918, 1925, 1941, and 1975 without people questioning their track record and abandoning the cult in despair.
To further demonstrate your authority, prophesy is essential. It is easiest to adopt an established prophetic text and offer a new interpretation in which its amorphous rhetoric predicts your cult in explicit, lucid terms. The books of 
As the interpreter of the prophesies, the Charismatic Leader embodies the spirit of knowledge itself. He must explain every ongoing event as it fits into whatever overarching scheme he has imposed upon the world. It is his responsibility to fudge any incongruities or failed predictions. Most of this is practical psychology and will be learned in time with experience. The Leader should enhance his power and influence by showing how he "predicted" events in the past which have already happened (or convincing people he has) or by making prophesies so ambiguous that they can be attributed to the next newsworthy event. Skim Revelation and Nostradamus for examples. Predictions must always be hopelessly vague, e.g. "The nation of nobility will suffer hardship, the economy will rise before falling again; technology will create a monster that devours the fruit of labor."
Exact date-setting should generally be avoided (unless you have the means to successfully reify your prediction) but a Great Disappointment doesn’t signify the end of a movement -- fast excuses can always be made and community bonds are always strengthened by hardship.