That's right Cindy, if Christ rose at dawn it would have been into the 4th day, but read Mat 18:1, He was already risen at dawn when the girls arrived. Lol
If Jesus was put into the Sepulchre just before sunset, say around 5:30pm in the evening, and He rose 72 hours later, he would have risen at 5:30PM Saturday evening just before the 1st day began.
I believe He actually rose right on the line between Sabbath, and the 1st day of the week, so even if it was a very end of the Sabbath Resurrection, it was still the 1st day of the week when he made all His appearances and made history as the first human to come back from a 3 day 3 night death.
JH :-)
Mark 16:1. And when the sabbath was past, Mary Magdalene, and Mary the mother of James, and Salome, had bought sweet spices, that they might come and anoint him.
2. And very early in the morning the first day of the week, they came unto the sepulchre at the rising of the sun.
JH :-)