How Old For First Haircut

I have seen babies as young as two months come in for their first haircut while others dont visit the salon until they are 2 years old. Some cultures are adamant about shaving newborns heads. Wach 2 Year Old Steals The Show During First Haircut Postrzyżyny was a pre christian all slavic tradition though it survived in poland well into the 18th century. How old