Start Time Increment Updates for Private Lessons

Our studio utilizes private lessons in 20 minute increments and we require private lessons for every solo, duet, and trio. Currently, we are unable to utilize the private lesson feature because we cannot book a private lesson outside of a 15 minute increment (4:00, 4:15, 4:30, 4:45). We need functionality to be able to start private lessons when we need to.