The Shehenshahi Calender of the Parsis
The Parsis in India are a spin off from the original Zoroastrians in what is today called Iran. The community fled the country when Muslim invaders began forcing conversions to Islam.
The fleet of ships they set course in from Iran landed in the region which is today the state of Gujrat in India. After obtaining permission from the King of Gujrat the community settled there.
They did absorb some local customs and traditions and modified others that they had brought with them from Iran. However they did not change the calender that they followed and still follow it to date.
Shehenshahi means "of the kings" and the Parsi calender comes from the ancient kings of Persia. The old calender is still followed to mark special occasions, festivals and of course the second birthday that most Parsis tend to celebrate.
So you have the first birthday as per the regular calender as everyone else does and the second birthday is as per the Roj of the Parsi Calender.
Names of the Months and Days as per the Parsi Calender are very different from the local Hindu calenders used in the region. The nomenclature reflects the Persian origin of the community and its sporadic use of the Persian language.
Mah and Roj - Months and Days
The Months or Mah of the Shehenshahi calender are
The last five days of the last month are collectively called the Mukhtad. At the end of the last month of the Parsi Calender there are five days called the Gathas. These days are restricted for prayers and at the end of the Gathas the new year begins. These are
The Days or Roj of the Shehenshahi Calender are
8 Dae - Pa- Adar
15 Dae - Pa - Meher
23 Dae -Pa - Din