In order to understand how Jesus was resurrected on Sunday before the Sun rose, we must first return to Genesis 1 to relearn what constitute a day.
It is here where God created the seven day week. On the first day He created light; however, God divided the light from the darkness. And God called the light day and the darkness He called night. AND THE EVENING AND THE MORNING WERE THE FIRST DAY (GEN 1:3-5).
Each creation day accounts ends with the same statement "And the evening and the morning were the 1st - 6th day." Gen 1: 1-31.
Thus, a day constitutes an evening (night) and morning (day), and begins at Sunset (evening) and ends Sunset (evening) - a 24 hour period. This is clearly manifested today with Orthodox Jews, Seventh Day Adventist, Baptist Adventist, and other religious denominations that keep the biblical Sabbath. When the sunset (evening) on Friday, Sabbath begins for them.
Therefore, Jesus was resurrected the third day (Sunday) before the sun arose because the day had already started the previous evening (Saturday night or sunset), which is both the start and end of a day.