ok, here is what I found on the subject. It is long, and deals more with passover type stuff, and symbolism between the jewish calender and the date that we beleive the priesthood was restored, but it also explains why we worship on Sunday rather than Saturday.
I have pasted the article as a whole so you can see what context I found it. That being said.... there is some in depth stuff here. If nothing else, see the "notes" at the bottom. Also at the bottom I have included the link to the article. You can better see the diagrams and tables there if you are interested, but that really does not have anything to do with the sat\sun stuff.
Passover Symbolism
In Part 1 it was proposed that the Savior’s resurrection occurred on the Sunday after Passover, 16 Nisan, or 3 April a.d. 33 on our Gregorian calendar. 2 But the relationship of his resurrection to the Jewish Passover is much more than just a coincidence of dates.
The Lord instituted the Passover celebration at the time of the exodus of the Israelites from Egypt, to commemorate their release from slavery after the angel of death slew the firstborn of Egypt but “passed over” the Israelite homes. (See Ex. 12.) However, as the symbolism of the Passover is reviewed, it will be clear that the Passover ceremony is not only symbolic of the redemption of Israel from bondage, it also was in similitude of the redemption of mankind from death and sin by the Lamb of God.
The prophets taught that the ordinances of the law of Moses (such as Passover) were symbolic of things to come. For example, Abinadi explained that “there was a law given them [the children of Israel], yea, a law of performances and ordinances, … all these things were types of things to come.” (Mosiah 13:30–31.) He summarized his powerful discourse, which condemned the wicked priests for not teaching the prophetic nature of the law of Moses, with the following closing statement: “Therefore, if ye teach the law of Moses, also teach that it is a shadow of those things which are to come—Teach them that redemption cometh through Christ the Lord.” (Mosiah 16:14–15; see also Mosiah 13:30–33.)
Similarly, Paul taught that the Law of Moses “was our schoolmaster to bring us unto Christ” (Gal. 3:24), and that it was “a shadow of good things to come” (Heb. 10:1).
How was the annual Passover ceremony a shadow of the redemption that would come through Christ? The Passover ceremony will now be reviewed to see how it symbolized not only the elements of the Atonement, but also their precise timing. (See “Calendar” and “Feasts” in the Bible Dictionary, LDS edition.)
The Passover feast centered on the paschal lamb, which was a sacrificial lamb, a male without blemish and with no broken bone, even after death. (See Ex. 12:5, 46.) Likewise, Jesus was the “Passover,” the “Lamb of God” (1 Cor. 5:7; John 1:29), a male without blemish and with no broken bone, even after death (John 19:36). He was the Firstborn of God in the premortal existence (D&C 93:21), sanctified in the flesh as were the firstborn of Israel (Ex. 12:23–24), and slain even as were the firstborn of Egypt (Ex. 12:29).
The Passover lamb was to be chosen on 10 Nisan, the tenth day of the Jewish lunar month Nisan. It was to be killed by “the whole assembly of the congregation of Israel” on 14 Nisan (Ex. 12:6), which was usually the day of the first full moon of spring. Jewish sources state that the lamb was sacrificed between 3:00 and 5:00 p.m. on that day. 3
Jesus, too, was “chosen” on 10 Nisan 4 at his triumphal entry into Jerusalem, when he was hailed as the Messiah (see Matt. 21:1–9; Mark 11:1–11; Luke 19:37–40; John 12:12–16), which had been prophesied by Zechariah (Zech. 9:9). The multitude who had assembled in Jerusalem for Passover later consented to his death when they “all” cried out on 14 Nisan, “Let him be crucified.” (Matt. 27:20–23.) The Lamb of God died about 3:00 p.m. (Matt. 27:46) on the day of preparation for Passover (John 19:14), 14 Nisan, just when the paschal lambs were also being slain.
Of course, at the triumphal entry the multitude did not understand that they were choosing the Lamb of God to sacrifice, but believed they were choosing a king (Luke 19:38) whom they expected to liberate them from Roman rule. And at the Crucifixion they were unaware that they were sacrificing the Lamb of God, but believed they were slaying an imposter who could not even save his own life. (Matt. 27:41–44.)
The preparation of the lamb for the feast had to be hurriedly completed before sunset, after which would begin the first day of Passover, 15 Nisan, a day sanctified as a special Sabbath day. After sunset, the lamb was eaten with bitter herbs, unleavened bread, and wine. This ritualized Passover meal was also called the feast of unleavened bread; it began a week in which no leavened bread was eaten, symbolic of the haste of preparation which did not allow enough time for bread dough to rise. (Ex. 12:18–20, 34, 39; Lev. 23:6–8.)
Likewise, the body of Jesus had to be hurriedly prepared for burial before the sunset would commence the Sabbath, which would be a “high day” (John 19:31) because it was not only Saturday, the weekly Sabbath, but also 15 Nisan, the first day of Passover.
It was on 15 Nisan, after the slaying of the firstborn, that Pharaoh declared liberty to the captive Israelites. After their long period of bondage in Egypt, it must have been a day of great rejoicing. One reason that 15 Nisan was sanctified as an annual feast day was to commemorate that day on which the Lord brought Israel out of bondage and released them from the chains of slavery. (See Ex. 12:14–17, 29–31; Ex. 13:3, 14–15.)
Similarly, on 15 Nisan a.d. 33, the Passover feast day, the Savior declared liberty to the captives in the spirit prison after their long period of bondage. (See D&C 138:18, 31, 42.) Before the Savior arrived, they had been “assembled awaiting the advent of the Son of God into the spirit world, to declare their redemption from the bands of death.” In fact, they were already “rejoicing in the hour of their deliverance from the chains of death.” (D&C 138:16, 18.) The fact that they were assembled, rejoicing in the hour of their deliverance, suggests that they expected his arrival on the Passover feast day, the day of liberation.
The law of Moses states that “on the morrow after the sabbath” of Passover, the priest should wave before the Lord a sheaf of the firstfruits of the harvest. 5 (See Lev. 23:10–12.) On Easter Sunday, 16 Nisan, the morning after the Jewish Sabbath, 6 the Savior, through his resurrection, became “the firstfruits of them that slept.” (1 Cor. 15:20, 36–38.) Jesus had already taught that he was like a kernel of grain which must abide alone until it dies in the ground, whereupon it can bring forth much fruit. (See John 12:23–24.) Lehi also explained that the Savior, “being the first that should rise … is the firstfruits unto God, inasmuch as he shall make intercession for all the children of men; and they that believe in him shall be saved.” (2 Ne. 2:8–9.)
Thus, the carefully prescribed elements of the Passover ceremony precisely foreshadowed both the events of the Atonement and the time each would occur. The annual sacrifice of the paschal lamb on 14 Nisan was not only in remembrance of the Israelites’ having been saved by the blood of the lamb on the houses in Egypt (Ex. 12:13), it was also anticipating the 14 Nisan when the great sacrifice of the Lamb of God would occur. The feast on 15 Nisan celebrated not only the liberation of the captives of Egypt; that day would also be the time of even more rejoicing when the Savior would declare liberation to the captives in the spirit prison. And the third day, 16 Nisan, was not only the time when the firstfruits of the harvest of barley were presented to the Lord, it was also the glorious day of the Resurrection—the firstfruits of the harvest of souls.
