One method for predicting an event is to follow the transits of the dasha lord. See this quote from sage Mantreshwara in the Phaladeepika:
"During the several periods over which a Dasha may continue, the good or bad effect is to be ascertained after referring to the particular house reckoned from the Moon, which the lord of the Dasha may occupy during the course of its progress through its orbit." Phaladeepika Ch 20 verse 60.
In this quote sage Mantreshwara emphasizes watching the dasha lords transit with reference to the Moon or chandra lagna, however, transits should also be seen from the ascendant. An extension of the above principle is to also follow the transits tothe dasha lord by other planets.
Here's an example chart of a man whose son was born while Jupiter was transiting over his mahadasha lord, Venus, during his Ven-Mer-Jup dasha. In this case Jupiter's transit is both a transitof the sub sub dasha lord (pratyantar dasha lord) as well a transitto the mahadasha lord, Venus.
He has Scorpio lagna with Jupiter being a multiple significator for children. Jupiter rules his 5th house, representing childbirth, from the lagna. Jupiter also rules the 9th house from the Moon, which is the 5th house from the 5th house, making it another house of childbirth according to the principle of bhavat bhavam. From Jupiter's placement in the sign of Virgo it also aspects the 5th house from the lagna (Pisces) which is also the 9th house from the Moon. Furthermore, Jupiter is also the karaka or significator of the 5th house for any ascendant.
At the time of his son's birth, Jupiter was transiting through the 5th house from the Moon, and transiting over Venus, the mahadasha lord, which triggered the event of childbirth. Saturn was also transiting through Aquarius putting the double transit of Jupiter and Saturn in the sign of Scorpio, which is the 5th house from the Moon further reinforcing that this was the timing for the birth of his son.
Transit on November 24, 1994