When rolling out of a shallow banked turn, when should you begin the roll out?

Beginning the roll out of a shallow banked turn about 10 degrees before reaching your desired heading is optimal because it allows for a smooth transition back to straight and level flight. When you start the roll out slightly before your target heading, it enables the aircraft to naturally return to level flight as the aircraft loses both bank and yaw.

During the turn, the aircraft is in a banked attitude, and as you start to roll out early enough, you account for the time it takes for the airplane to respond to the control inputs. This timing helps to avoid over- or under-rolling, which can result in a less coordinated and potentially awkward transition that may lead to altitude loss or gain, and can also affect comfort in the cockpit.

Being aware of your heading and having a systematic approach to rolling out ensures better control of the aircraft throughout the maneuver, contributing to safer and more precise flying.