Agniveshyagrihyasutra 2.3.2.2

2.3.2.2

āpūryamāṇapakṣe puṇye nakṣatre śvaḥ kariṣyāmīti śvo bhūte vānnaṃ saṃskṛtya śucīn śrotriyān brāhmaṇānāmantrayate \

In the waxing fortnight, on an auspicious asterism, thinking "I will perform [it] tomorrow," or on the next day having prepared the food, he invites pure, learned Brahmins.