In Jain dharma there is no specific tithi or festival mentioned in scriptures like “From this day you must start eating mango.” The rules are based on ahimsa and seasonality, not on a fixed date.

Very simply:

1. Only when it is naturally in season

- Mango should be eaten only in the time of year when it grows and ripens naturally in your region. - Off‑season mango usually means more himsā (transport, storage, chemicals, etc.).

1. Only when it is properly tree‑ripened

- Ideally the mango should ripen on the tree or with minimum artificial help. - Chemically ripened or forcibly ripened fruits are discouraged because they involve extra violence to subtle life forms and can harm health.

1. Check for living beings (worms/insects)

- If you see infestation, it should not be eaten, to avoid killing the beings inside.

1. Before sunset, in limited quantity

- Like other foods, for a practicing Jain it is best taken before sunset. - Over‑indulgence is also against the principle of aparigraha (non‑possessiveness).

1. Monks vs. householders

- Sadhus/sadhvīs are much stricter and often avoid such rich fruits, or eat only what is given without special desire. - Śrāvaks/śrāvikās (householders) may eat mango, but following the above principles of minimum himsā and simplicity.

In some Jain communities there are local customs like starting mango after a certain Hindu tithi (e.g., after Akṣay Tritiyā), but these are community traditions, not a universal Jain scriptural rule.

So, as per Jainism, you should start eating mango only when it naturally comes in season in your area, is properly ripened with minimal violence, and eaten with restraint and before sunset.