April Seventh, 1928
Faulkner starts his novel with such a disorienting chapter because he has his main character, Benjy Compson, the mentally retarded son of the Compson family, narrate everything in his point of view. In Benjy's point of view he has a voice of a child, he is aware and observant to everything that is going on around him, but can tell the story in a disorienting tone with the ongoing change of time periods. Maybe that was Faulkner's point so that he can relate those different periods of time and Benjy's experience through those times, to see how they affect actual human experiences in every day life. When we tell a story that has happened in the past we reflect through our point of view, which is what Faulkner is having Benjy do to relate to human experience. So Faulkner starts off the chapter in Benjy's disorienting point of view so that the reader can tell what is going throughout the chapter, like what time period they are in and what Benjy remembers from then because he is constantly thinking of the past. He has no perception of the time period he is actually in, he just sees something from the present and it immediately triggers something from the past that makes him relive that memory that has him thinking he is actually in that time period he is thinking of.
Benjy's status in the Compson family is pretty low. He is the runt of the litter, he is seen as a mistake that cannot fend for himself and the Compson family is just stuck with him. Benjy is basically raised by the Gibsons because his mother cannot stand to care for him for fear of her status and appearance. The Gibsons try their best to be patient with him, but think he is a blubbering idiot that can't do anything without their help. Benjy is also seen as lower than the Gibson's even because here is a grown white man that comes from a high and proper family, that cannot even take care of himself because he has the mind set of a three year old. Even though Benjy cannot really do anything for himself, he can still understand somewhat of what is going on in his family. His role with the Compson family is being observant to what is going on and to sense things that will happen in the future. He plays a very innocent role in his not so innocent family. His unique perspective about his family tells us that Uncle Maury is an alcoholic, his mother is too proud and way too concerned about appearances, and Caddy smells like trees and doesn't care about what anyone thinks about her. His family is very cautious about Benjy and they don't want anyone to see the way he is because they care too much about their status.
Benjy is dependent on the consistency of family and past memories because he cannot rely on himself  since everyone else takes care of him. He goes back to the memories of when he was younger because in the present, the things that are occuring may bring stress to Benjy which causes him to retreat back to those old memories. Because now his family is even more ashamed of him since he is grown and mentally retarded. This says that his family is full of pride and caught up in appearances more in the present than they were in the past. Maybe Faulkner is saying the South can be very judgemental?
Is Benjy a symbol? I would think he is a symbol of everything that is wrong in the Compson family because he tells the story in his point of view of all the wrong his family has done which worsens over time. The same goes with Benjy, because over time his mental illness worsens. He is a three year old stuck in a thirty three year old mans body.