When did Mary Magdalene discover that the stone was rolled away?
On the first day of the week, early, before daylight while it was still dark, Mary Magdalene came to the sepulcher and discovered that the stone had been taken away. This occurred on resurrection morning, at the tomb where the body had been placed in a cave.
Les explains that John 20 opens on resurrection morning. As was the custom, they anointed the body of the deceased with herbs and spices even a day or so after burial. They were not buried underground as we think; they were placed in a cave. Mary Magdalene, verse 1 says, came on the first day of the week early, no doubt before daylight, when it was dark, and discovered the stone taken away. Peter and John hear it from Mary and run full speed to the sepulcher. John, the athlete, got there first but was more timid; Peter bursts right in, and then John joins him in the sepulcher.
The first day of the week cometh Mary Magdalene early, when it was yet dark, unto the sepulchre, and seeth the stone taken away from the sepulchre.