Is it permissible to celebrate the advent of the month of Ramadan by holding food and drink gatherings if they are free of prohibitions and constitute an old custom?

Celebrating the advent of Ramadan (definition) was not known among the righteous predecessors, including the Prophet, peace and blessings be upon him, his companions, and those who followed them. They did not celebrate by holding feasts and providing food. Therefore, this is considered an innovation (bid'ah). Old customs do not justify permissibility. Goodness lies in following his guidance, peace and blessings be upon him, and evil lies in innovating in religion. However, a Muslim should be keen to spend in charitable ways, especially in Ramadan, by feeding those who are fasting and giving charity to the needy.