While the Brit Milah is a millennia old tradition in Judaism there has never been one formal ritual or ceremony for welcoming a baby girl into the Jewish people. Different communities in different times have used a variety of rituals, and many more have been updated or even created in recent decades as Judaism has become more egalitarian.
The ceremony for a girl has no fixed time. Some parents have chosen to perform a ritual within a few days of birth, some on the 8th day to parallel the Brit Milah, some on the first Rosh Chodesh (new Hebrew month) since Rosh Chodesh is a holiday associated with women, some after the baby is a month old, some on the child’s first birthday, and some on a date that is simply convenient for friends and family to gather together.
The ceremony can be as simple as the parents receiving an aliyah (being called to the Torah) where the Rabbis and Hazzan will bless the couple and announce the child’s Jewish or Hebrew name. Or the ceremony can be as elaborate as a Brit Milah, with prayers to welcome the child into the covenant, a ritual act such as wrapping the baby in a talit, holding the baby with a Torah, or washing the baby’s feet, a formal announcing of the child’s name, and additional blessings. The Rabbis can help you determine what ceremony or ritual would be best for your family.