After you file

Ok I filed 1/7/19, Accepted 1/17/19, and after several phone calls I received a 4883c letter in the mail on 3/18/19 (two months after being accepted). Today I called and verified with a very pleasant IRS rep. Now the wait begins. I wonder what happens if my return hasn't been processed by 4/15/19? Will I have a late penalty?? I will post if I receive any updates. Keeping hope alive!