A student intending to make changes to their schedule once the quarter starts should be mindful of specific add and drop deadlines. These are available on the Registrar’s website, in addition to the detailed course description on schedule builder: 

Academic Calendars
Add and Drop Deadlines 

The two primary add deadlines are: 
10th day of instruction – 10 day drop deadline 
20th day of instruction – 20 day drop deadline 
Last day of instruction – last day to cancel/withdraw or use a Permission to Drop number