The Great Sabbath
The Sabbath immediately preceding Passover is called Shabbat HaGadol, which in Hebrew means "the great Sabbath". According to tradition, the 10th of Nisan in the year of the exodus was a Saturday (spoiler alert - it was also on a Saturday nearly 1500 years later when Jesus was crucified). It was considered a great event, in fact a miracle, that the Israelites could on that day select a lamb (associated with the Egyptian God Amun) for the Passover sacrifice without being punished by their Egyptian masters. Killing a lamb would have been deeply offensive for the Egyptians as lambs were considered to be sacred. An interesting side note is that lambs figured prominently in temple offerings for Egyptians as well.
Source: Code of Jewish Law, Orach Chayyim 430:1, https://halachipedia.com/index.php?title=Shabbat_HaGadol#cite_note-1
The miracle of the Great Sabbath began a Passover tradition. It was on this Sabbath that the Lord commanded the families of Israel to obtain a lamb for sacrifice and bring it to their homes. This would be the Korban Pesach - the Passover lamb to be sacrificed on the 14th (Exodus 12:3). The tradition has continued for Israel to select its paschal lamb on the 10th to bring the lamb into the home four days before Passover to inspect and make sure it is without blemish.
Given the deep symbolism of Israel selecting the lamb that would be used as the Passover lamb, the one whose blood would deliver them, the events of the annual Great Sabbath align very precisely with what happened during the year of the Exodus.
On Sunday, the passover lamb was selected and brought into the homes of Israelites to be inspected for blemishes before being slain four days later.
On the exact day of the Great Sabbath, when Israel would choose their pascal lamb, the Lamb of God was chosen by Israel.