The story is told in the form of a flashback. Miss Emily has died at the beginning of the story, but to understand what happens after her death, we have to go back into her past. We also have to understand the social/historical changes that Faulkner uses. First, we have the description of Miss Emily confronting the townsmen who have come to demand her taxes. With our modern concept of property taxes, it would never occur to any of us to question the idea that she must pat what is owed to the county in order to keep her land. But, to understand her refusal, we have to understand first the role of the Southern gentleman. When Colonel Sartoris tells her after the death of her father that she will owe no taxes, he is "taking care" of this helpless orphaned young woman. Neither he nor anyone else of his generation would question the fact that Miss Emily is to be cared for in this way. Of course, no one lives forever, nor did the idea of one man being powerful enough to make such a decree. As far as she was concerned, the Colonel's word was his bond; therefore, she need never concern herself with taxes. In Miss Emily's world, when a gentleman gave his word it was not cancelled by something as mundane as his death.
Another example of time changing in the story revolves around Miss Emily and her "china painting" classes. There were very few occupations that a "lady" of her social standing could participate in and still retain the status of a lady according to the social rules of the time. Faulkner points out that all of the young ladies of a certain period were sent to Miss Emily to learn this delicate art because that is what refined young women did, but as time passed, the art was not one that modern women found pleasure or interest in. As her students drifted away, Miss Emily remained, caught in the time capsule of her youth and bound by the social rules that she was raised with.
Then, we have the man-servant. For years he not only cared for Miss Emily's home, but he also kept her secret. There was no way that he didn't know about Homer's rotting corpse in the bedroom at the top of the stairs. But, because his obligation, his loyalty was to Miss Emily, he would never reveal what he knew. That kind of loyalty from a paid servant, one who was most likely the child of slave parents is not one that we understand today. But it was his loyalty that kept her secret. When she died, he continued with this loyalty by opening the front door and walking out the back, never to be seen again.
You see, the time that Faulkner marks in this story is more than time measured in years, weeks, or days. It is the marking of change measured by time.
The story starts off describing her death and the funeral, then gives background on her family and father. Then it launches into a description of the aldermen coming to collect the taxes, and how she vanquished them. Right after this Faulkner writes,
"So she vanquished them, horse and foot, just as she had vanquished their fathers thirty years before about the smell."
Right after this, we get another time marking:
"That was two years after her father's death and a short time after her sweetheart...had deserted her."
These are the two clearest indicators of a timeline that we get. The story continues, giving the details about the smell and how they applied lime to get rid of it. Then it describes her father's death, her refusal to release the body until three days had passed, then how after that "she was sick for a long time." These references to time are less clear. There are mentionings of days passing during the Homer Barron part of the story, and then after he disappears, and she is seen very little. The next mentioning of time is "a period of six or seven years, when she was about forty" when she gave painting lessons. And, that is is for specific mentionings of times.
The most clear indications of time is in the first examples. I hope that helps!