Notes: All timings are represented in 24-hour notation in local time of New Delhi, India with DST adjustment (if applicable).
Hours which are past midnight are suffixed with next day date. In Panchang day starts and ends with sunrise.
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 (षोडशोपचार) Puja Vidhi. Please check Krishna Janmashtami Puja Vidhi which lists all Puja steps for Janmashtami along with Vedic Mantra to perform the Puja.
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.
Most of the time, Krishna Janmashtami is listed on two consecutive days. The first one is for Smarta Sampradaya and the other one is for Vaishanava Sampradaya. Vaishanava Sampradaya date is the latter one. A single date for Janmashtami means that both Sampradaya would observe Janmashtami on the same date.
However many people will notice unanimity in North India on choosing the day to celebrate Krishna Janmashtami. The reason behind this unanimity is the institution of ISKCON. The International Society for Krishna Consciousness, commonly known as ISKCON is founded on the principles of Vaishnava traditions and most followers of the ISKCON are the followers of Vaishnavism.
With all due respect, ISKCON is one of the most commercialized and global religious institutions which spend money and resources to promote ISKCON brand and ISKCON culture. In North India, most people observe Janmashtami on the day chosen by ISKCON. Many people who are not the followers of Vaishnavism do not even understand that ISKCON traditions are different and the most appropriate day to observe Janmashtami fasting might not be the same as that of ISKCON.
Smarta followers who understand the difference between Smarta and Vaishnava sectarian do not follow ISKCON date to observe Janmashtami fasting. Unfortunately, ISKCON date to observe Janmashtami is unanimously followed in Braj region and most common people who just follow the buzz observe it on the date followed by the ISKCON.
People who are not the followers of Vaishnavism are followers of Smartism. Hindu religious texts like Dharmasindhu and Nirnaysindhu have well-defined rules to decide Janmashtami day and those rules should be followed to decide Janmashtami day if one is not the follower of Vaishnava Sampradaya. Ekadashi fasting is one of the good examples to understand this difference. Rules to observe Ekadashis' fasting are also different for Smarta and Vaishnava communities. However, there is more awareness about different Ekadashi rules followed by Vaishnava sectarian. Not only Ekadashis, Vaishnava fasting day for Janmashtami and Rama Navami might be one day later than Smarta fasting day.
The followers of Vaishnavism give preference to Ashtami Tithi and Rohini Nakshatra. The followers of Vaishnavism never observe Janmashtami on Saptami Tithi. Janmashtami day according to Vaishnava rules always fall on Ashtami or Navami Tithi on Hindu calendar.
However, rules followed by Smartism to decide Janmashtami day are more complex. The preference is given to Nishita Kaal or Hindu midnight. The preference is given to the day, either Saptami Tithi or Ashtami Tithi, when Ashtami Tithi prevails during Nishita and further rules are added to include Rohini Nakshatra. The final consideration is given to the day which has the most auspicious combination of Ashtami Tithi and Rohini Nakshatra during Nishita time. Janmashtami day according to Smarta rules always fall on Saptami or Ashtami Tithi on Hindu calendar.
This page list Janmashtami according to Smarta Sampradaya as well as ISKCON.