Notes: All timings are represented in 12-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.
Bilva Nimantran is done during Shashthi Tithi while it prevails during Sanyakal. Sometimes Shashthi ends before Sanyakal but prevails during Sanyakal on previous day i.e. on Panchami Tithi. If it happens then Sanyakal on Panchami Tithi is considered more suitable for doing Bilva Namantran.
Most people during Durga Puja take Shashthi Tithi for Kalparambha, Bodhon and Adhivas & Amantran irrespective of it prevailing during Sanyakal or not. According to religious texts combination of Sanyakal and Shashthi is the most appropriate time for Bilva Puja.
However, Navpatrika Pravesh is always done on Saptami Tithi even if Bilva Nimantran is done on Panchami due to non-availability of Sanyakal Shashthi on the next day.
The main rituals on the first day of Durga Puja, which mostly falls one day before Navpatrika Puja, are Kalparambha, Bodhon and Adhivas & Amantran.
Kalparambha is done early in the morning preferably during Pratahkal. Kalparambha rituals consists of installing the water filled Ghata or Kalash, offering worship to Goddess Durga and taking Sankalpa, the firm determination to conduct the Puja ritualistically during the next three days namely Maha Saptami, Maha Ashtami and Maha Navami.
Bodhon which is also known as Akal Bodhon is performed during Sanyakal. Bodhon means awakening and as name implies Goddess Durga is symbolically awakened during this ritual. According to Hindu mythology all Gods and Goddesses go to sleep for six months during Dakshiyana. Because Durga Puja falls in the middle of this period, the Goddess Durga is first awakened before worshipping. The first awakening of Goddess Durga was done by Lord Rama who wanted to propitiate the Goddess before fighting ten headed Demon Ravana. Due to untimely awakening of Goddess Durga Bodhon ritual is also known as Akal Bodhon.
The ritual of Bodhon consists of installing a water filled Kalash or vessel at the base of Bilva tree. Bilva tree is also known as Bel tree whose leaves are the utmost sacrosanct for Shiva Pujan. During Bodhon prayers are offered to awaken Mother Durga.
Adhivas and Amantran rites are done after Bodhon. Invocation of Goddess Durga is known as Avahana (आवाहन) and symbolically installing Goddess Durga in Bilva after Avahana is known as Adhivas (अधिवास). Bilva tree is also sanctified before installing Goddess Durga into it during Adhivas rites.
After Adhivas, Goddess Durga is given invitation to accept the Navpatrika Puja on the next day. Inviting Goddess Durga ritualistically is known as Amantran (आमंत्रण).