While following the Vakhya Panchangam, at all locations a nakshtram or tithi can be considered to exist for the same nazhigai from sunrise. For those who follow Drik Panchangam, these calculations could differ.
Dwadasi did exist for a short duration on the day after March 21st. For such occurrences, Dwadasi paranai is done on the day of the tail-end (Puccha) of Dwadasi tithi and Ekadasi fasting is on the day before.