Srimad Bhagavatam Canto 08, Chapter 18, Text 13

SB 8.18.13

tam vatum vamanam drstva
 modamana maharsayah
karmani karayam asuh
 puraskrtya prajapatim
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
When the great sages saw the Lord as the brahmacari-dwarf Vamana, they were certainly very pleased. Thus they placed before them Kasyapa Muni, the Prajapati, and performed all the ritualistic ceremonies, such as the birthday ceremony.
 
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
According to Vedic civilization, when a child is born in the family of a brahmana, the birthday ceremony, known as jata-karma, is first performed, and then other ceremonies are also gradually performed. But when this vamana-rupa appeared in the form of a vatu, or brahmacari, His sacred thread ceremony was also performed immediately.
Srimad Bhagavatam Canto 08, Chapter 18, Text 12
Srimad Bhagavatam Canto 08, Chapter 18, Text 14