There is a continuous discourse in astrological circles here and in India on the much-vexed subject of timing of marriage
Some veteran astrologers cite principles relating to marriage enshrined in classical on Astrology while some others speak from their personal experience as career astrologers. 

Certain Indian astrologers say that the year and the month of marriage can be predicted precisely and accurately going by the Sun’s transit in the Rashis in the Natal Chart and the Navamsa Chart.

However, an astrologer making an attempt at timing of a marriage has to, in the first place, ascertain whether there are indications that the native would embark on matrimony. 

Impediments preventing or delaying marriage
Let us consider at the outset a few astrological factors that operate as impediments preventing or delaying marriage. 

•  Mars in Virgo and Saturn in Cancer or Pisces become obstacles to an early marriage.
•  The conjunction, mutual exchange of signs and mutual aspect between Saturn and Moon or Saturn and Sun are also positions leading to delaying marriage.
•  Venus in Cancer or Leo hemmed in between Sun and Moon denies marriage.
•  Afflicted 7th and 8th Houses delay or deny marriage.
•  A slow-moving planet in the 9th House delays marriage.
•  There would be a long delay in marriage if the 9th lord occupies the 6th, 8th or the 12th House along with Jupiter.
•  There would be no marriage at all if the Sun and Saturn, Venus and Moon and Mars and Saturn are in close conjunction or are in mutual aspect. If the distance between Sun and Venus exceeds 43degrees, there would be obstructions to marriage. 

Sun’s transit
According to classical works on Astrology marriage of those born in Uttarayana occurs when Sun enters the Navamsa Rashi of Jupiter or its trinal Rashis while being aspected 
by Jupiter.

Marriage of those born Dakshinayana takes place when the Sun enters the Navamsa Rashi of Venus or its trines while being aspected by Jupiter.

Marriage also takes place when Sun is in the Navamsa Rashi of the Lagnadhipati while Jupiter is posited in the Lagna.

Marriage can take place when Sun transits the 1st, 5th, 7th or the 9th House while being aspected by transiting Jupiter.

Marriage can take place if transiting Sun fails to receive the aspect of transiting Jupiter, but when receiving the aspect of natal Jupiter.

Factors causing early marriage
Following astrological factors also contribute to an early marriage:

•  The 2nd lord is in the 11th House and the 11th lord is posited in the 2nd House. This is also a Dhanayoga.
•  The 2nd lord is in the 11th and the 10thlord is in the Lagna
•  Lagnadhipati is in a sign owned by Saturn and Venus is in a quadrant.
•  Venus is in a quadrant or Kendrasthana and Saturn is posited in the 7th from Venus 
•  Sun is in the 7th with Venus as the 7th lord. (Sun in the 7th without this connection with Venus would only postpone the marriage)
•  An exalted or Swakshetra 7th lord occupies a Moolatrikona or the 4th or the 7th.
•  Mars in a sign or a Navamsa owned by Venus and the latter is in a sign or a Navamsa owned by Mars or both together in one sign. The 7th lord and Venus or in trines or quadrants hemmed in between benefics while receiving the aspect of benefics.

Venus, Mars and Moon singly or together command the power to cause an early marriage. Mars – Venus combination hastens the marriage, but the native would become immoral if the conjunction occurs in Taurus or Capricorn.

Jupiter is also Mangala Yoga-karaka and marriage can take place in his Maha Dasa or Antar Dasa.