You are expected to meet your classes on time and for the time interval scheduled. Classes are not expected to get out early.

A "three hour" class is scheduled for 185 minutes per session and is allowed 20 total minutes of break time per session. "Two hour" classes are scheduled for 125 minutes per session and are allowed 10 minutes of break time per session. If your class meets for less than two hours, there are no breaks.

It is not usually good policy to save all the break time for the end of the class period so as to get out early, nor to use the break time at the start of class so as to start late. Your students need some break time even if you don't.