I'm going to use Mark as it is the earliest Gospel. Mark 15 says that Jesus was crucified at nine in the morning. At three in the afternoon, that same day, Jesus dies. Verse 42 tells us what day this is, the day of preparation, or the day before the Sabbath.
Sabbath started in the evening, at sundown. It was just before this that the body of Jesus was taken from the cross and put into the tomb. In other words, this happened Friday night according to western reckoning.
Chapter 16 then opens with, "when the Sabbath was over..." So from sundown on Friday, to sundown on Saturday, nothing occurred. At this point, some women are buying spices to anoint the body of Jesus. So that is happening on Saturday evening.
Verse 2 states that these women went to the tomb very early in the morning, on the first day of the week, which is Sunday. By the time they arrive, Jesus is gone. So we have to assume that Jesus had been gone for at least a little time by the early morning on Sunday.
So we are looking at a time period (according to Mark) from Friday night, to maybe Sunday morning. That is not 3 days and 3 nights. That is pretty much 1 day, and 2 nights.
Matthew and Luke follow the same basic timeline.
Let's take a closer look:
Christ's crucifixion took place on Passover day, the 14th of Abib (or Nisan), the first month in Gods Sacred Calendar. This occurred in the year A.D. 31, in which Passover fell on a Wednesday. Many fail to consider the prophecy that the Messiah would be "cut off
in the middle of the week" (Dan 9:26-27). Wednesday falls in the middle of the week--the very day upon which Passover fell in A.D. 31.
That Passover was a preparation day, in that it preceded an annual Sabbath. This annual Sabbath (called the First Day of Unleavened Bread) was called a high Sabbath or "high day" (John 19:31) and fell on a Thursday that year. It was on this day that the high priest and the Pharisees came to Pilate to ensure that Christs tomb was securely guarded and sealed (Matt. 27:62-66).
Mark 15:42 refers to Friday which is also a preparation day (any day before any Sabbath-high or weekly-is a preparation day). Mark 16:1 records what took place on that Friday: "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." (Verse 2 jumps to Sunday morning.) The phrase, "and when the Sabbath was past," refers to the high day that occurred on Thursday. Since the women could not buy spices on the seventh-day Sabbath (Saturday), Friday was the only time they could have done so.
Luke 23:56 states, "And they returned, and prepared spices and ointments; and rested the sabbath day according to the commandment." After buying the spices, they returned and prepared them to be applied to Christs body in the tomb, which they planned to do after resting on the weekly Sabbath.
Luke 24:1 states, "Now upon the first day of the week [Sunday], very early in the morning, they came unto the sepulcher, bringing the spices which they had prepared, and certain others with them." The women found the tomb empty (vs 3). Two angels in shining garments informed them that Christ was already risen (vs. 4-6). Mark 16:2 states that the women were present "at the rising of the sun. This means Christ was resurrected before sunrise.
John 20:1 further tells us that Mary Magdalene came early "when it was yet dark" and found the stone that sealed the tomb was already rolled away. At this point, Christ was already resurrected. He was resurrected sometime Saturday evening--three days and three nights later, just as He prophesied.
The chart in point 6 is a detailed, chronological timeline that may help visualize the sequence of events:
http://www.religiousforums.com/forum/2900803-post106.html