The Edut L'Yisrael (a text on sources for customs surrounding weddings and births in Judaism, published in Israel c. 1960) brings sources for the custom to learn and post the night before the brit, as well as make a festive meal.
According to Edut L'Yisrael (a text on Jewish customs surrounding weddings and births in Israel from approximately 1960), it provides sources for the custom of learning and posting a notice the night before the brit ceremony, along with organizing a festive meal.