Hadith.4729 - Ali ibn Ja'far asked his brother Imam Musa ibn Jafar Al-Kadhim (as) about a newborn whose head was not shaved on the seventh day.
Imam (as) replied: "If seven days have passed, then shaving the head is no longer required."
Al-Kāfi #149“I once asked abu al-Hassan (a.s.), about the newborn: if shaving his head after seven days from his birth is required. He (the Imam) said,...
Al-Kāfi #150“Abu ‘Abd Allah (a.s.), has said, ‘When seven days from the birth of a child pass, then it is not ‘Aqiqah (the way it should have been).”’