The link below finds a list of the sessions and dates of the first through the current Congress, 1789- present. The list is at the website of the U.S. Senate.
Since 1934, the first session of a Congress convenes on January 3rd of odd-numbered years and adjourns on January 3 the following odd-numbered year. (For example, the 116th Congress began January 3, 2019 and will adjourn January 3, 2021.)