Joel describes the end of the age, the last seven years as beginning with the festival of trumpets.
After the festival of trumpets there was a 10 day period where we were to reflect on our sins, give a careful accounting of the previous year (in this case the entire age) and prepare to meet our God. That meeting takes place at the Day of Atonement.
After the festival of trumpets there was a 10 day period where we were to reflect on our sins, give a careful accounting of the previous year (in this case the entire age) and prepare to meet our God. That meeting takes place at the Day of Atonement.