For Jains, the main rule about mango is when to stop, not when to start.

According to Jain niyam:

• Mango can be eaten in its season as usual, before Ādrā (Adra) Nakshatra.
• From Ādrā Nakshatra onward, mango (keri) should be given up, because from this time tiny insects/larvae are believed to develop inside the fruit, and eating it can go against ahiṁsā.

For the year 2026:

• Ādrā Nakshatra (Keri Tyāg) falls on Monday, 22 June 2026.
• So, Jains should eat mango only up to Sunday, 21 June 2026 (before sunset).
• From 22 June 2026 onwards, you should stop eating mango for that year.

You can read more detailed explanation about mango and Ādrā Nakshatra here

Also general Jain guidance on mangoes: