John Calvin Commentary Genesis 30:22

"And God remembered Rachel, and God hearkened to her, and opened her womb." — Genesis 30:22 (ASV)

And God remembered Rachel. Since with God nothing is either before or after, but all things are present, he is subject to no forgetfulness, so that, in the lapse of time, he would need to be reminded of what is past. But the Scripture describes the presence and memory of God from the effect produced upon us, because we conceive him to be such as he appears to be by his acts.

Moreover, whether Rachel’s child was born last of all cannot be determined with certainty from the words of Moses. Those who, in this place, affirm that the figure hysteron proteron, which puts the last first, is used, are motivated by the consideration that if Joseph had been born after the last of his brothers, the age that Moses records in Genesis 41:46 would not accord with the fact.

But they are mistaken in this: they reckon the nuptials of Rachel from the end of the second seven years, whereas it is certainly proven from the context that although Jacob agreed to serve for Rachel, he obtained her immediately, because from the beginning, the strife between the two sisters broke forth.

Moses clearly intimates, in this place, that the blessing of God was bestowed late, when Rachel had despaired of having children and had long been subject to reproach because of her barrenness. Because of this prosperous omen, she gave the name Joseph to her son, deriving the hope of two sons from the prospect of one.