Esther & Chronology
A quick read through the book of Esther might leave the impression that all of the events in the book transpired within six months. However, there are three references in the book to specific dates in the reign of King Ahasuerus (Xerxes I).
The first banquet took place in the third year of his reign, 483 BC (Est 1:3).
Esther became queen in the seventh year of his reign, 478 BC (Est 2:16).
Haman hatched his plot to destroy the Jews in the 12th year of Ahasuerus. Because this happened in the first month of the year, it was likely less than five full years after Esther had become queen, probably early in 474 BC (Est 3:7).
Finally, when Haman cast the lot to determine the date for the extermination of the Jews, it came up as the twelfth month of that year. Because their calendar began the New Year in March/April, the twelfth month would have been the equivalent of early 473 BC. Of course, this turned out to be the deliverance of the Jews, not their extermination.
A timeline that shows these events as well as the broader historical setting is available here.