Canto 1 - Boyhood
Bāla-kāṇḍa
Chapter 18: The Advent of Rāma, Lakṣmaṇa, Bharata and Śatrughna
Text 1.18.21

अतीत्यैकादशाहं तु नामकर्म तथाकरोत्॥

atītyaikādaśāhaṁ tu nāma-karma tathākarot

atītya = after; ekādaśa-aham tu = eleven days; nāma-karma = the nāma-karaṇa; tathā akarot = King Daśaratha performed.

After eleven days, King Daśaratha performed the nāma-karaṇa.

The ceremony was conducted eleven days after Lakṣmaṇa’s birth (twelve days after Rāma’s birth). The Smṛti states that kṣatriyas should conduct this ceremony after twelve days.[12] Performance of this ceremony in consideration of the first son is appropriate. The nāma-karaṇa was conducted with great festivities, like the jāta-karma ceremony.

[12] kṣatriyasya dvādaśāhaṁ sūtakam.