Nick says that the incidents he focuses on in the story "were merely casual events in a crowded summer," and that his "personal affairs" took up far more of his time. He says that most of the time he worked, rising early to travel into New City to his job at the Probity Trust. He would lunch with his coworkers on "little pig sausages and mashed potatoes and coffee." He mentions a "short affair" with a young woman working in another department.
Nick would often eat dinner at the Yale Club, and then would study investments in the Yale Club library for a "conscientious hour." Afterwards, if the evening were pleasant, he would stroll around New York City, enjoying the constant flow of people. He sometimes would feel lonely and would imagine himself entering into other people's lives "and no one would ever know or disapprove." He also would notice the poorer clerks.
He mentions losing track of and then taking up again with Jordan Baker.
From this, we learn that Nick spends most of his time that summer working, being lonely in the big city and dating Jordan. Daisy, Tom and Gatsby are hardly at the center of his life.