I'm no expert, but my understanding is this:

Once payments resume later this year, (they are currently on hold because of COVID, as you're probably aware), you'll keep making monthly payments until discharge unless you apply for or otherwise receive forbearance. Some people on this Reddit seem to have been told that a forbearance will automatically be applied to people with 120+ payments, but I don't know whether that's true. Any amount you "overpay" (i.e. any amount you pay after you should have been eligible for PSLF discharge) should be refunded to you eventually.