I applied to harvard ea on the Thursday before the due date, and I haven’t been contacted thru phone or email about an interview. When do they usually schedule that? Will they do so through phone or email?
Thanks 
Take a deep breath! Inhale! Exhale! Breathe!
Now that you are zen-like calm, be assured that once you press the submit button, your contact information is automatically forwarded to your nearest alumni association. The AA will then assign a member to interview you.
Your interviewer will most likely contact you by **email/b. However, depending upon the number of applicants and the number of alumni interviewers available, you may not be contacted for several weeks, so relax. The interview is thought by many – including alumni interviewers themselves – to be the LEAST important part of the process. FWIW: If you are applying from one of the following countries, you should initiate contact with an interviewer once you have submitted your Common Application: https://college.harvard.edu/admissions/application-process/what-we-look/interviews