Our Sunday readings are part of a lectionary, pre-selected readings. There are two lectionaries in the back of the Book of Common Prayer. One is for Sunday services, it is a three year cycle, labeled by letters ("A", "B", "C"). The other is a "Daily Office" lectionary, it is a two year cycle, labeled 'Year One' and 'Year Two'. If one follows these you will read most of the Bible over two years.
A number of years ago the Episcopal Church voted to follow the "Revised Common Lectionary" on Sundays, rather than the one in the prayer book. This aligns us with many other 'connected' churches, such as the Roman Catholic, Methodist and Lutheran Churches. This means on most Sundays we hear the same readings as friends and family in these churches and have common ground for conversation! That's right, you can share something from a sermon on Sunday (hint, hint) with a friend that attends another church and they may have heard a sermon on the same passage!
Both lectionaries 'begin' on 1st Advent. We are currently in 'Year A', but will soon switch to 'Year B'. This three year cycle focuses on a different Gospel each year, but includes readings from each Gospel. This past year our emphasis has been on Matthew (Year A), and soon we will focus on Mark as we enter Year B.
The daily lectionary also hinges on Advent 1. I remember what year we are in by thinking that "odd" years, such as 201'7' are Year 1 and "even" years, such as 201'8' are Year 2. The only exception is the season of Advent... of course all of this is made easier when you can use a lectionary website to provide the correct readings. I hope this insight into where we get our readings helps to connect you to our readings.
Additionally, there are dozens of great readings plans that can help guide your reading of scripture. Each has it's advantages, my hope and prayer is that we all spend some time with the scriptures each week. This immersion into the story helps encourage and inspire us as we aspire to follow Christ.