Krishna Janmastami

Krishna Janmashtami in Jaipur Devotees, who observe fast on Janmashtami, should have the only single meal a day before Janmashtami. On fasting day, devotees take Sankalpa to observe a day-long fast and to break it on the next day when both Rohini Nakshatra and Ashtami Tithi are over. Some devotees break the fast when either Rohini Nakshatra or Ashtami Tithi is over. Sankalpa is taken after finishing morning rituals and the day-long fasting begins with Sankalpa.
The time to perform Krishna Puja is during Nishita Kaal which is the midnight as per Vedic time-keeping. Devotees perform detailed ritualistic Puja during midnight and it involves all sixteen steps which are part of Shodashopachara Puja Vidhi. Please check Krishna Janmashtami Puja Vidhi which lists all Puja steps for Janmashtami along with Vedic Mantra to perform the Puja.

Fasting Rules on Krishna Janmashtami
No grains should be consumed during Janmashtami fasting until the fast is broken on next day after Sunrise. All rules followed during Ekadashi fasting should be followed during Janmashtami fasting also.
Parana which means breaking the fast should be done at an appropriate time. For Krishna Janmashtami fasting, Parana is done on next day after Sunrise when Ashtami Tithi and Rohini Nakshatra are over. If Ashtami Tithi and Rohini Nakshatra do not get over before Sunset then fast can be broken during the daytime when either Ashtami Tithi or Rohini Nakshatra is over. When neither Ashtami Tithi nor Rohini Nakshatra is over before Sunset or even Hindu Midnight (also known as Nishita Time) one should wait to get them over before breaking the fast.
Depending on end timing of Ashtami Tithi and Rohini Nakshatra fasting on Krishna Janmashtami might continue for two complete days. Devotees who are not able to follow two days fasting might break the fast on next day after Sunrise. It has been suggested by Hindu religious text Dharmasindhu. Krishna Janmashtami is also known as Krishnashtami, Gokulashtami, Ashtami Rohini, Srikrishna Jayanti and Sree Jayanthi.

History of Janmashtami
Mathura was being ruled by the evil King Kansa, who had a sister called Princess Devaki. Devaki was married to Vasudeva with a lot of fanfare, however, Kansa got to know that there was a prophecy according to which their eighth son would cause his downfall.

When informed about this, Kansa at once imprisoned Devaki and Vasudeva. He got their first six children killed, the seventh child, called Balram, was mystically transferred from Devaki’s womb to that of princess Rohini, who stayed in Vrindavan. After their eighth child was born, Vasudeva managed to rescue child Krishna and took him to Vrindavan, where he gave him to Nand and Yashoda.

Vasudeva then came back to Mathura with a girl child to give to Kansa, so that he wouldn’t kill her. However, Kansa still tried to kill the baby by throwing her on a huge rock. However, as he tried to do this, she transformed into Goddess Durga, warning him about his death.