The Season of Advent begins four Sundays before Christmas (December 1, 2019) and ends after the mid-afternoon prayer on Christmas Eve (December 24, 2019).
The Christmas Season begins with Evening Prayer on Christmas Eve (December 24, 2019) and ends with Evening Prayer on the Feast of the Baptism of the Lord (January 12, 2020).
Ordinary Time begins after Evening Prayer on the Feast of the Baptism of the Lord (January 12, 2020) until Ash Wednesday (February 26, 2020).
The Season of Lent begins on Ash Wednesday (February 26, 2020) and ends with the Celebration of the Evening Mass of the Lord’s Supper on Holy Thursday (April 9, 2020).
The Paschal Triduum begins on Holy Thursday with the Evening Mass of the Lord’s Supper (April 9, 2020) and ends with Evening Prayer on Easter Sunday (April 12, 2020).
The Easter Season begins on Easter Sunday (April 12, 2020) and ends with Evening Prayer on the Solemnity of Pentecost (June 7, 2020).
Ordinary Time begins after Evening Prayer on the Solemnity of Pentecost (June 7, 2020) and continues until Evening Prayer of the First Sunday of Advent (November 29, 2020).
http://stmarymysticalrose.org/liturgical-seasons