The 15th is Sunday, and no regular work was to be done that day ALSO. The Women did not attend Christ,s grave that Sunday, because it was against the law.
The Passover and the Festival of Unleavened Bread
4 “‘These are the Lord’s appointed festivals, the sacred assemblies you are to proclaim at their appointed times: 5 The Lord’s Passover begins at twilight on the fourteenth day of the first month. 6 On the fifteenth day of that month the Lord’s Festival of Unleavened Bread begins; for seven days you must eat bread made without yeast. 7 On the first day hold a sacred assembly and do no regular work.
On the first day of the Festival of Unleavened Bread is a Sabbath, the "high day"
John 19:31 Therefore, because it was the Preparation Day, that the bodies should not remain on the cross on the
Sabbath (for that Sabbath was a high day), the Jews asked Pilate that their legs might be broken, and that they might be taken away.... 42 Therefore on account of
the Jewish day of preparation, because the tomb was nearby, they laid Yeshua there.
Luke 23:52
…this man (Joseph of Arimathea) went to Pilate and asked for the body of Yeshua. 53 And he took it down and wrapped it in a linen cloth, and laid Him in a tomb cut into the rock, where no one had ever lain. 54 And
it was the preparation day, and the Sabbath was about to begin.
After this Sabbath [first day of the Feast of Unleavened Bread] had passed, you have preparation day for the weekly Sabbath. The women could not obtain the necessary items to properly anoint His body and bury Yeshua. However, once the High Sabbath was over, the women could buy what they needed for this task.
Mark 16:1 And
when the Sabbath was over, Mary Magdalene, and Mary the
mother of James, and Salome,
bought spices, that they might come and anoint Him.
On the day after the High Sabbath, the women purchased the spices and spent the day preparing them to anoint Yeshua’s body. However, they were once again delayed, this time by the weekly Sabbath.
Luke 23:55 Now the women who had come with Him out of Galilee followed after, and saw the tomb and how His body was laid. 56 And
they returned and prepared spices and perfumes. And
on the Sabbath they rested according to the commandment. 1 But
on the first day of the week, at early dawn, they came to the tomb, bringing the spices which they had prepared.