The day nothing done is lost. Kept at madhyahna — read at sunrise it dates a day late.
Akshaya Tritiya is Vaishakha Shukla Tritiya — the Tritiya of the shukla fortnight of Vaishakha. It is kept at midday, so the date is the day that tithi is running madhyahna, the middle of the daylight hours.
Computed from the Moon’s elongation with the Swiss Ephemeris, sidereal, Lahiri ayanamsa. A tithi begins and ends at a real minute rather than at midnight, which is why the moment above decides the day — and why the same tithi read at a different hour can name a different date.
Cast a free kundli, or ask any of 24 astrologers what this year actually holds for you. Billed by the minute, and only while somebody is answering.