This depends on a few factors such as your flow and the capacity of the cup. Generally, the maximum amount of time you should wear a menstrual cup is ~10-12 hours consecutively. It should be emptied, washed, and rinsed a minimum of 2-3 times daily and can be worn overnight.
Most people flow 2-6 ounces during their menstrual period, and emptying the cup a few times a day is usually adequate. During days when your flow is heavier, you will need to empty the cup more frequently to avoid leaking. After sustained usage, you’ll become more familiar with your own menstrual flow pattern.