Previously: One of the sabbaths
To see why Mary might have gone to the tomb while it was still dark, instead of waiting even for the first rays of dawn, we have to look at first century Hebrew culture again. The Hebrew Sabbath began at sundown on Friday, and continued until sundown on Saturday. After sundown on Saturday, for the Jew, it was now the first day of the week, the 7th day being over. So the dark of Saturday evening, to a Jew, is the first day of the week. We, thinking like Romans, don’t consider it the first day of the week until we get up in the morning on Sunday, but 1st century Jews did not think like Romans. They thought like Hebrews.
During the Sabbath, from sundown Friday to sundown Saturday, work was prohibited. In order to set the day apart from the rest of the week (which is what keeping the day holy means) they greeted the Sabbath on Friday evening with a special ceremony, and they bid the Sabbath farewell on Saturday evening with a special ceremony. In between the ceremonies, no work was done.
The Friday evening ceremony usually consisted of a special family meal in their homes; special prayers and blessings were said, and special food was served. Sunday dinner at Grandma’s is the American equivalent in concept. Then the Jews gathered together twice on Saturdays: in the morning, in the synagogue, to hear the Torah reading, and the readings from the Psalms and the Prophets, and the teaching on the readings. The Gospels record one instance where Jesus gave the teaching on the reading from the Prophets in one synagogue meeting.
Then in the evening, as it was drawing toward sundown, the Jews gathered again, usually in homes, for a havdallah service: a special ceremony in which the Sabbath was bid goodbye. This Saturday evening meeting often lasted well into the night, as it was an opportunity for fellowship which did not occur during the rest of the week.
The meeting in Acts 20:7 was most likely a havdallah service. Paul did not preach from Sunday morning until midnight (not really humanly possible, for the preacher or the listeners); but from Saturday at sundown, at the close of the Sabbath, until midnight. Either meaning for "one of the sabbaths" could apply in Acts 20:7: the meeting began on "the first of the sabbaths" as we can see from reading the verse in its context with Acts 20:6; and it ended on "the first day of the week," as Jews considered the dark of the night Saturday night to be the first day of the week.
So back to John 20:1: it was Mary’s desire to anoint the body of Yeshua with spices for His burial, but because He was taken down from the cross so close to sundown before a Sabbath, it could not be done right away. The best she could do was prepare the spices, then wait for the Sabbath to be over before she anointed the body. If I put myself in Mary’s shoes, and my heart was heavy with love and grief for my Lord, and I knew that His body had been put into the tomb unanointed, I would want to anoint His body as soon as possible. It could not, however, be done on the Sabbath: at any time in between the opening and closing ceremonies. But the very next opportunity would be as soon as the closing ceremony was over, on Saturday night or Sunday morning. (We know from Jewish tradition, and Acts 20:7, that these meetings went well into the night, Saturday night and Sunday morning.) If it were me, I would have taken the spices with me to the havdallah service, so that I could go straight to the tomb when the service was over. And this is what I believe she did: she most likely took the spices with her to the havdallah service, so that, on her way home, the Sabbath being over, she could go to the tomb and anoint the body. Thus she could do the work the love in her heart for her Master was urging her to do as soon as possible, while not violating the Sabbath.
So it being yet dark, on the first day of the week to a Jew (sometime Saturday night or Sunday morning to a Roman); the Sabbath being over, she went to the tomb, and found the stone already rolled away.
Could I be wrong about this? Of course. But this understanding does not violate the meaning of the Greek; it does not violate first century Hebrew traditions and practice, and it does not contradict other places in the Scripture which portray Yeshua and His followers as obedient to God, and keepers of the Law of Moses, including the Sabbath.