Get into the Swing of Things

To become accustomed to routine activities.

In the 1500s the phrase, "in full swing," meant to be very active in something. "Swing" could have come from the motion of a children's swing of a clock pendulum. In the 1800s a new expression developed that was based on the old one: "get into the swing of things." That meant getting involved with whatever was going on, especially society.

It took her two weeks at her new job but she finally got into the swing of things.

(From the "Dictionary of Idioms," Marvin Terban, Scholastic Inc., publisher, 1996)