In Jainism, the jiva (life/soul) is considered eternal and begins its journey in many forms through rebirths. A new life in a womb is marked by the Garbha Kalyanak (conception), which is one of the five auspicious life-events (Panch Kalyanaks) for a soul. This means conception is viewed as the moment a new life begins in that birth, while the soul itself is already immortal and has no absolute starting point. For Tirthankaras, the Garbha Kalyanak is a noted event with specific traditional locations, and the same idea applies to other jivas as they undergo rebirth. You can read more about the Panch Kalyanaks, including Garbha Kalyanak, here .