John Calvin Commentary Psalms 105:23

"Israel also came into Egypt; And Jacob sojourned in the land of Ham." — Psalms 105:23 (ASV)

And Israel came into Egypt. The prophet does not recount the whole history, nor was this necessary. He only presents to us how divine providence was involved in it, which very few consider in reading the narrative of Moses.

Therefore, he declares that after Joseph had been sent ahead into Egypt as the means to support his father and the whole family, Jacob then came into Egypt. He did so when all things were wonderfully arranged, so that he might find an abundance of bread among a people, the proudest of the whole world, when all others were perishing from lack of food.

From this, it appears that what is considered to be slowness in God serves no other purpose than to accomplish his work at the most opportune moment.