Types of admission (rolling admission, early action)

Hi guys! I’m a rising senior and I’m looking for CLEAR information about rolling admission. I understand that rolling admission basically means that applications will be evaluated upon being submitted and the applicant should hear back shortly. I am still however slightly confused. For example lets say I was applying to Harvard and they had rolling admission which began in October. If I sent my application in on Sept 1st would I not hear back until rolling admission begins in October or could I hear back sooner?
I’m just confused about the advantages of rolling admission.
just as a frame of reference the schools I am applying to that have rolling admission are University of Pittsburgh, Rutgers University, Duquesne University, and Seton Hall University.
Thank you and any other advice you have about applying to colleges is welcome!

. “For example lets say I was applying to Harvard and they had rolling admission which began in October.”
Harvard and other top colleges dont have rolling admissions.
For colleges that DO have rolling admissions, and there aren’t that many, the BENEFIT is that if accepted, you KNOW you WILL be going to college somewhere! That can be a huge relief!
If however, you are rejected early, then that can be an important wake up call that perhaps you need to revise your college list , and aim lower.

If RA BEGINS on Oct 1, then sending your application on Sept 1 might mean that your application is read sooner than an application sent in on Sept 2, but NO, it does not mean that you can have your results before Oct 1!