All slow cookers vary in their heat output, as does how warm or not your kitchen is, as well as the moisture content of the bananas, and so forth. Therefore, the total time will range. However, I would plan on about 3 hours, but definitely start checking at about 2 to 2 1/2 hrs into the cooking process to see how it's looking. Bread is done when a toothpick inserted in the center comes out mostly clean and no wet batter.