This story is written in the minimalist style.  The author gives very little detail to the backstory of the characters or to description.  We enter the story in the midst of things - Alfred has already been stealing, we don't see the beginning of that.  The reason Callahan does this is to focus the attention of the audience.  The important part of this story is the coming of age that happens for Alfred, when ‘‘his youth seemed to be over’’.  In his mother's reaction to his actions, Alfred is finally able to mature and to see outside of himself.  ‘‘It seemed to him that this was the first time he had ever looked upon his mother."  He recognizes the needs and feelings of others for the first time.  This is a sudden realization, often common to a coming of age.  Time is important here to portray that Alfred's change is the work of a moment, and not of a long series of events.  Time is also important in limiting the audience so that Alfred's epiphany has more force.  If Callahan had included more "time" in the story - more days, more events - than the quiet moment of Alfred watching his mother at the kitchen table would not have the force that it did.