In this Samskara the bachelor is given “ Gayatri Upadesha” by the Acharya and the teacher teaches the bachelor about Vedas and behavioral code of conduct and disciplines of Brahmacharya Ashrama. After Upanayana the person is called Dwija or reborn. He is said to have taken rebirth from the womb of Acharya. After this samskara the person wears a sacred thread called Yagnopaveetham. The Yagnopaveetham contains three threads reminding the person that he has to pay his three debts called Pitru, Rishi and Deva runam.
Timing: Counting the age from the birth or conception, the age prescribed is 5th to 8th year for Brahmins, 6th to 11th year for Kshatriyas and 8th to 12th year for Vaisyas. The maximum age limit is 16 years for Brahmins, 22 years for Kshatriyas and 24 years for Vaishyas. Solar months of Makara, Kumbha, Meena, Mesha, Vrishabha and Mithuna are considered good. Upanayana of eldest son should not be done when Sun is in Vrishabha. Upanayana is to be performed during Uttarayana only.
Nakshatras: All fixed nakshatras (Uttara triam, Rohini), all friendly nakshatras (Mrigasira, Revati, Chitra and Anuradha), Allshort nakshatras ( Hasta, Aswini, Pushyami and Abhijit) and all movable nakshatras( Swati, Punarvasu, Sravanam, Dhanishta and Satabhisham) are considered to be good. Punarvasu is not considered to be good for Brahmins.
Tithis: 2,3,5,10,11 and 12 tothis of both bright and dark half are auspicious.
Days: All days except Tuesday and Saturday are good. For Samavedis, even Tuesday is good. Part of the day: Divide the length of the day in three parts. Upanayana is considered auspicious in first part of the day.
Lagna: In Upanayana lagna, benefics placed in kendras and Trikonas and Malefics in 3,6,11 houses are considered good. Jupiter, Moon, Venus and lagna lord should not be in Trik houses and should not be conjoined with malefic. Strength of Jupiter is an important condition in Upanayana. The 5th house should be strong and 8th house should be vacant. Proper Tarabala and Chandra bala should be seen for both Acharya and Vatu, i.e., teacher and student. As so many above-mentioned factors are to be observed, it is very difficult to fix a muhurta for Upanayana.