Manava Dharmashastra 2.34

2.34

caturthe māsi kartavyaṃ śiśor niṣkramaṇaṃ gṛhāt
ṣaṣṭhe 'nnaprāśanaṃ māsi yad veṣṭaṃ maṅgalaṃ kule //

In the fourth month the Nishkramana (the first leaving of the house) of the child should be performed, in the sixth month the Annaprasana (first feeding with rice), and optionally (any other) auspicious ceremony required by (the custom of) the family.