November 15 is Shichi-go-san, a day of prayer for the healthy growth of young children. Shichi-go-san literally means seven, five, three; in most regions around the country, boys and girls aged three, boys aged five, and girls aged seven visit a Shinto shrine with their parents. Most girls wear kimonos when making their Shichi-go-san visit, while boys don haori jackets and hakama trousers.
By the Edo period (1603-1868), this practice spread to commoners, who began visiting shrines to have prayers offered by priests. The Shichi-go-san customs followed today evolved in the Meiji era (1868-1912). November 15 was chosen for this celebration because it was considered the most auspicious day of the year, according to the traditional Japanese calendar. Because the date is not a national holiday, most families pay their Shichi-go-san respects on the weekend just prior to or after November 15.

Following the visit, parents generally buy chitose-ame (longevity candy) for the children. The candy is shaped like a stick and comes in a bag that carries illustrations of cranes and turtles--two animals that are symbols of long life. Chitose literally means a thousand years and is used to denote very longnperiods of time. The candy and the bag are both expressions of parents' wish that their children lead long, prosperous lives.

I don't know why it has been carried out so early, my sister has promised to ask.