They have now been with me three days

When people of Israelites under the slavery of Egypt, God asked them to take three days journey and sacrifice to the Lord - And they will listen to your voice, and you and the elders of Israel shall go to the king of Egypt and say to him, The Lord, the God of the Hebrews, has met with us; and now, please let us go a three days' journey into the wilderness, that we may sacrifice to the Lord our God - Exodus 3:18, Exodus 5:3, Exodus 8:25-27, Exodus 10:26

but after the red sea crossing no one talked about the three days journey, And Bible tells that the people of Israelites did not make any offering on third day - Then Moses made Israel set out from the Red Sea, and they went into the wilderness of Shur. They went three days in the wilderness and found no water. When they came to Marah, they could not drink the water of Marah because it was bitter; therefore it was named Marah. And the people grumbled against Moses, saying, “What shall we drink?” And he cried to the Lord, and the Lord showed him a log, and he threw it into the water, and the water became sweet. There the Lord made for them a statute and a rule, and there he tested them - Exodus 15:22-25

Because, according to exodus one day means 430 years - Now the sojourn of the children of Israel who lived in Egypt was four hundred and thirty years. And it came to pass at the end of the four hundred and thirty years - on that very same day - it came to pass that all the armies of the Lord went out from the land of Egypt - Exodus 12:40-41

And after three days, that means after 1290 years, the one who spoke to Moses said three days are over in the desert land of Israel - In those days, the multitude being very great and having nothing to eat, Jesus called His disciples to Him and said to them, I have compassion on the crowd, because they have been with me now three days and have nothing to eat. And if I send them away hungry to their homes, they will faint on the way. And some of them have come from far away - Mark 8:2-3

And then he went to the cross -  And He Himself is the propitiation for our sins, and not for ours only but also for the whole world - 1 John 2:2

That was the reason Christ asked this question to the scholars - And the Pharisees and Sadducees came, and to test him they asked him to show them a sign from heaven. He answered them, “When it is evening, you say, ‘It will be fair weather, for the sky is red.’ And in the morning, ‘It will be stormy today, for the sky is red and threatening.’ You know how to interpret the appearance of the sky, but you cannot interpret the signs of the times - Matthew 16:1-3

NOTE: And from the day of departure (red sea crossing) the Israelites supposed to observe unleavened feast for 7 days, and if they want to offer the sacrifice on the third day, it will be in the middle of the 7 days unleavened feast, so its very clear what God said from burning bush about 3rd day journey should be calculated differently.

This day shall be for you a memorial day, and you shall keep it as a feast to the Lord; throughout your generations, as a statute forever, you shall keep it as a feast. Seven days you shall eat unleavened bread. On the first day you shall remove leaven out of your houses, for if anyone eats what is leavened, from the first day until the seventh day, that person shall be cut off from Israel. On the first day you shall hold a holy assembly, and on the seventh day a holy assembly. No work shall be done on those days. But what everyone needs to eat, that alone may be prepared by you. And you shall observe the Feast of Unleavened Bread, for on this very day I brought your hosts out of the land of Egypt. Therefore you shall observe this day, throughout your generations, as a statute forever. In the first month, from the fourteenth day of the month at evening, you shall eat unleavened bread until the twenty-first day of the month at evening. For seven days no leaven is to be found in your houses. If anyone eats what is leavened, that person will be cut off from the congregation of Israel, whether he is a sojourner or a native of the land. You shall eat nothing leavened; in all your dwelling places you shall eat unleavened bread - Exodus 12:1-20

Who can keep the promise for 1290 years and fulfill it, only God can do that, So come to Jesus Christ.