Sometimes the effects of transits do not occur when you expect them to. There could be a number of possible reasons for this. First of all, the last verse in the chapter entitled 'Gocharaphala' (the fruits of transits) in the classic text Phaladeepika says that the planets each give their fruits by transit in different drekkana's of a sign. A drekkana is simply a division of three, which is why the 3rd divisional chart (D3) is also called the drekkana chart. Therefore, the drekkana of a sign, which is thirty degrees, is 10 degrees. The first 10 degrees of a sign is the first drekkana, 10-20 degrees is the second drekkana, and 20-30 degrees is the third drekkana. Here is the quote:
"During their transit Mars and the Sun produce their results when they occupy the initial 10 degrees or figure Drekkana (1st Drekkana) of a sign. Jupiter and Venus show their effects when they are in the middle portion of a sign (2nd Drekkana). While the Moon and Saturn are productive in the last portion (3rd Drekkana). Mercury and Rahu produce their effects all through their passage."
- Phaladeepika ch 26, verse 25.
Thus, this can be listed as:
- Sun, Mars: 1st Drekkana (0-10 degrees of a sign)
- Jupiter, Venus: 2nd Drekkana (10-20 degrees of a sign)
- Moon, Saturn: 3rd Drekkana (20-30 degrees of a sign)
- Mercury and Rahu (Ketu): any portion of sign.
This is definitely a useful guideline, but if there's anything I've learned in the seventeen years I've practiced Jyotish it's that no principle works all the time. But it will usually work most of the time. There are many places to cross the river as the saying goes. Therefore, each principle is important to remember and weigh in the overall assessment of a chart. Here are a couple other principles about transits that explain why the above principle doesn't work all the time.
- Transits are generally secondary to the dashas. Therefore, if the dasha doesn't line up for the event to happen, while the transit is happening, then the event may not come to fruition. For instance, the event that's being triggered may be marriage. The person has Aquarius rising and the Sun rules the 7th house. They're in their Sun-Ketu dasha and during this dasha the Sun enters into Leo (7th house) by transit. The dasha lord transiting through its own sign in the 7th house could indicate a time for marriage. The Sun generally gives its effects by transit in the first 10 degrees of a sign as the above quote states. However, the marriage may not take place until Venus sub-dasha begins. Venus is the karaka for marriage, and Venus follows Ketu in the dasha sequence. By that time the Sun could still be transiting through the 7th house but may be in the last drekkana, instead of the first drekkana, and the event takes place. The Sun could also have transited out of the sign entirely and the event still could take place in the Sun-Venus dasha.
- Transits generally give their effects while the planet is within a 0-8 degree orb from another planet. For instance, the event that's being triggered is the signing of a financial contract with a partner. The transit that could be triggering this event could be Jupiter conjunct with Mercury. Mercury could be placed natally at 28 degrees of Sagittarius as the 7th lord in the 10th house. The event may occur as Jupiter enters the third drekkana of Sagittarius by transit and approaches natal Mercury. However, generally speaking Jupiter's events by transit occur while it is in the middle portion or the 2nd drekkana of a sign, as stated in the Phaladeepika quote above.