If you are looking to get your chart calculated, you can find various Panchangam details via official sources like the India Meteorological Department
The Vimshottari Dasha (planetary periods) is calculated using the Moon's Nakshatra. Since the Nakshatra may differ in Vakya, your starting Dasha (balance of Ketu, Venus, or Sun) may differ entirely from your Drik chart. A Vakya Dasha often predicts timing of events (marriage, job, accident) with a shift of 1–2 years compared to Drik. vakya panchangam based horoscope
The primary debate in Tamil astrology is the difference between these two systems: Vakya Panchangam If you are looking to get your chart