How long should the woman who found a single gold earring in her son's school wait before it becomes her property, knowing that she wishes to contact the school to publicize it better?

Whoever finds money belonging to another person that has value, it is obligatory for him to publicize it for a full year by announcing it in places where he believes its owner might recognize it, such as the places where it was picked up, markets, mosque entrances, and newspapers. The money remains with him as a trust during this period. If its owner does not appear after the year has passed, he may take possession of it and benefit from it, provided that he guarantees its value if its owner is found. He may also give it as charity; if its owner approves, the reward will be for the owner, otherwise, the finder guarantees it and the reward for the charity returns to him.