Many preachers will contend, and I agree, that the Israelites suffered needlessly at the hands of Pharoah after the death of Joseph, and then the rise of another king who did not know Joseph or the Lord God.
"Now therefore fear the LORD, and serve him in sincerity and in truth: and put away the gods which your fathers served on the other side of the flood, and in Egypt; and serve ye the LORD." (Joshua 24: 14)
The Israelites were worshipping other gods while slaves in Egypt, and even after the LORD had delivered them from their slavemasters, rescued them, and even when they switched covenants, so to speak (Exodus 19: 8), and afterwards, as they wandered in the wilderness for forty years.
Keep in mind, furthermore, that Joshua was speaking to the new generation, the Israelites who were too young to rebel against the commandment of the LORD in Numbers 13 and 14 to take the land which God had already given them.
So, many would rightly conclude that the Israelites wasted a great deal of time.
Yet let us look back to the Covenant promise which the LORD had made to Abram:
"13And he said unto Abram, Know of a surety that thy seed shall be a stranger in a land that is not theirs, and shall serve them; and they shall afflict them four hundred years; 14And also that nation, whom they shall serve, will I judge: and afterward shall they come out with great substance." (Genesis 15: 13-14)
God had predicted that the Israelites would be slaves. He also predicted that they would leave Egypt with great substance.
But also, while the Israelites were slaves in Egypt, the giants of the land of Canaan were preparing the homes, farms, and wells for the Israelites:
"And it shall be, when the LORD thy God shall have brought thee into the land which he sware unto thy fathers, to Abraham, to Isaac, and to Jacob, to give thee great and goodly cities, which thou buildedst not, 11And houses full of all good things, which thou filledst not, and wells digged, which thou diggedst not, vineyards and olive trees, which thou plantedst not; when thou shalt have eaten and be full; " (Deuteronomy 6: 10-11)
So, even though the Israelites were wasting their time, so to speak, as slaves in Egypt serving other gods, the LORD God Almighty , who declares the end from the beginning (Isaiah 46:10), and at the very moment when the Israelites cried out over their oppression, God heard them and readied their deliverance:
"23And it came to pass in process of time, that the king of Egypt died: and the children of Israel sighed by reason of the bondage, and they cried, and their cry came up unto God by reason of the bondage. 24And God heard their groaning, and God remembered his covenant with Abraham, with Isaac, and with Jacob. 25And God looked upon the children of Israel, and God had respect unto them." (Exodus 2:23-25)
We can speed up the release of God's grace in our lives by crying out early and often that we need Him, and that apart from Him, we can do nothing. Yet us also remember that for God, a day is as one thousand years, and vice verse (2 Peter 3: 8), and that He can bring the most fantastic miracle out of the most ordinary (John 2: 9) and even the most dire (Mark 9: 24) situations something beyond what we can ask or think (Ephesians 3: 20-21).
Don't regret lost time. Turn to Him boldly in your time of need (Hebrews 4: 16), and receive His grace, and behold Him make all things, no matter how bad, work for your good (Romans 8: 28)