All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
There is no basis in Islam for a given celebration after a period of four months and four days following the birth of a new baby. Whoever celebrates it as a religious rite, in fact, practices an innovation.
According to the Sunnah, one can chew a date and then put it in the baby's mouth right after his birth.
For more benefit, please refer to Fatwa 82088.
Allah knows best.