3 cards = sun, moon & ascendant for astrological timings
I've done a few readings using this system, but I did them a few years ago so the full details aren't as fresh in my mind as I'd like. In a nutshell, working with Arabic lunar mansions and the corresponding Arabic alphabet letters according to Ibn Arabi, the 56 Minor Arcana cards may be assigned in pairs to each of the 28 lunar mansions. The astrological correspondences between some of the minors and the decans helps with this process. The Majors can be added into the mix by the correspondences between the Arabic and Hebrew alphabet letters. Somewhere I have a list of how I did all that if anyone is interested. Anyway, once each tarot card has an associated zodiacal range, draw 3 cards, with the first signifying the location of the sun in a horoscope, the second corresponding to the moon and the third to the Ascendant. Past or future event timings can then be found by using an ephemeris or astrology program or website to find out the last (or next) time the sun, moon and ascendant had (will have) those relationships.