Short Answer

The gestation (Garbh) period of all 24 Tirthankaras is traditionally considered to be six months before their descent (Garbh-kalyanak), during which auspicious signs appear indicating their forthcoming birth.

Detailed Explanation

According to Jain scriptures and traditional accounts, each of the 24 Tirthankaras undergoes a special gestation period marked by divine auspicious events. The auspicious influence and indications of a future Tirthankara start appearing six months before their conception or descent, known as Garbh-kalyanak. This period is significant as it marks the spiritual and physical preparation for the Tirthankara's birth.

During this six-month gestation, the being destined to become a Tirthankara already possesses threefold knowledge (Mati, Shruti, and Avadhi Jnan) and does not feed on the mother's milk after birth. Various divine beings and goddesses attend to the Tirthankara's needs during and after birth, performing rituals and celebrations.

This six-month Garbh period is consistent for all 24 Tirthankaras in the Bharat and Airavat areas during each ascending and descending time cycle.

References

• APPENDIX 1, Jainworld: https://jainworld.jainworld.com/jainbooks/tirthankar/apendix-1.htm