Upanayanam

The ceremony was typically performed at age eight among the Brahmins, at age 11 among
the Kshatriyas, and age 12 among Vaishyas.[3][18] Apastamba Gryha Sutra, in verse
1.1.1.27, places a maximum age limit of 24 for the Upanayana ceremony and start of formal
education. However, Gautama Gryha Sutra and other ancient texts state that there is no age
restriction and anyone of any age can undertake Upanayanam when they feel they initiate
their formal studies of the Vedas.

Significance
The boy gains the right to study Vedas through this ceremony.
This allows a Brahmin boy to enter into Brahmacharya Avastha.
The three threads stand for Brahma, Vishnu, and Siva.
Done on an auspicious date compatible to Janma Nakshatra of the boy.

When to Perform Upanayanam Ceremony?
When the male child attains the age of 8 years this ceremony is performed by fixing a
Muhurth based on the birth nakshatra of the boy.

Benefits of Upanayanam Ceremony:
The Boy is now eligible ready to learn all vedas and he is now allowed to perform.
He is protected from all kinds of evil spirits and negative energies.