In Lois Lowry's novel The Giver, children begin volunteer hours after their Ceremony of Eight. At this Ceremony, the children begin their metaphorical initiation into adulthood. Their comfort objects are taken away from them, and they are given jackets with pockets which symbolize their newfound responsibility for keeping track of their own possessions. They begin their volunteer hours by selecting an area of service where they would like to give their time. Despite the pretense of free will that is offered up in this choice, these hours serve as a "test run" for their future career within the Community. The children are carefully surveyed by the Elders, who will decide whether or not the selected area of service would be a good fit for the child's actual job.
This job, or "assignment," is given at the Ceremony of Twelve. It is at this point that the children have completed all their volunteer hours, ending their volunteer work, and start an actual job.
In the book The Giver by Lois Lowry, a very structured society is depicted. The ages of society members do not start with the date of their birth, but rather there is a communal ceremony once a year for the purpose of naming and rites of passage that denotes a "year" for each child as opposed to a true age. Children start volunteer hours at year eight and are given a career path when they reach year twelve, ending their time as a volunteer.
While career paths are assigned to an individual by the Elders, volunteer hours are less directed and the choice of how children spend their volunteer hours is often factored in to the Elders' decision for the child's future career. It also appears that the number of hours performed by each child is left to the child's discretion as it is mentioned that a year eleven child in the past had not performed enough volunteer hours to be given a career. While this has negative impacts (it is mentioned that there was much shame associated with not getting a career), it is still a choice that can be made. The Giver also mentions an instance of a year eleven dedicating all of his hours to one specific area, indicating that it may be possible to volunteer in multiple fields.