It varies from person to person. It also depends on what you define as your benchmark for “learn to play the piano”, how well you take to the learning process, and how much time you put in to practice. Typically, learning to play an instrument is a long term process. With most students, it can take up to a year of dedicated lessons and practice to see discernible results. In other words, when you are considering taking lessons, aim to commit to the long game.