Dhantrayodashi, also known as Dhanteras is the first day of five days Diwali festivities. On the day of Dhantrayodashi, Goddess Lakshmi came out of the ocean during Sagar Manthan. Hence, Goddess Lakshmi, along with Lord Kubera who is the God of wealth, is worshipped on the auspicious day of Trayodashi. However, Lakshmi Puja on Amavasya after two days of Dhantrayodashi is considered more significant.
Lakshmi Puja on Dhanteras or Dhantrayodashi should be done during Pradosh Kaal which starts after sunset and approximately lasts for 2 hours and 24 minutes.
Choghadiya Muhurat is not advised to perform Dhanteras Puja as those Muhurtas are good only for travelling. The best time for Lakshmi Puja on Dhanteras is during Pradosh Kaal when
Sthir Lagna prevails.
If Dhanteras Puja is done during Sthir Lagna, Lakshmiji will stay in your home. Vrishabha Lagna is Sthir and generally overlaps with Pradosh Kaal during Diwali.
Hence, exact window for Dhanteras Puja should contain Pradosh Kaal and Sthir Lagna while Trayodashi is prevailing.
Yamadeep is another ritual on the same Trayodashi Tithi when the lamp for the God of death is lit outside home to ward off any untimely death of any family members.
Glossary:
Trayodshi: 13th tithi, or lunar days, from the New Moon (Amavasya) and Full Moon (Poornima)
Pardosh Kaal: Pradosh Kaal is the time when the day and night meet. Pradosh Kaal is an auspicious time and is known for worshipping Lord Shiva.
Pradosh Kaal is a specific period, which occurs daily. Pradosh Kaal is calculated at exact moment of Sunset by adding two Muhurtas or four Ghatis, which is equivalent to 96 minutes.
Pradosh Vrat: It is the fasting on Trayodashi Tithi and worshipping Lord Shiva at the time of Pradosh Kaal on that day. Hence, Pradosh Kaal occurs daily, but Pradosh Vrat is performed on specific lunar day only.
Sthir Lagna: Means fixed lagna, i.e 2,5,8, 11.