Christmas season in Italy is traditionally celebrated December 24-January 6, or Christmas Eve through Epiphany. This follows the pagan season of celebrations that started with Saturnalia, a winter solstice festival, and ended with the Roman New Year, the Calends. However there are lots of Christmas things to see during December prior to Christmas, many starting on December 8, the Feast Day of the Immaculate Conception.Italian Christmas Traditions
Although Babo Natale (Father Christmas) and giving presents on Christmas are becoming more common, the main day for gift giving is Epiphany, the 12th day of Christmas when the three Wise Men gave Baby Jesus their gifts. In Italy, presents are brought by La Befana, who arrives in the night to fill children's stockings. More about Epiphany and La Befana.
Christmas decorations and trees are becoming more popular in Italy. Lights and decorations are often seen starting around December 8, the Feast Day of the Immaculate Conception, or even the end of November. The main focus of decorations continues to be the presepe, Nativity scene or creche. Almost every church has a presepe and they are often found outdoors in a piazza or public area, too.
( text from: http://goitaly.about.com/od/christmasinitaly/a/christmas.htm)