Paul says in Galatians 3:17 that the 430 years starts with Abraham receiving the promise, and ends with Moses receiving the law.
Abraham received the promise when he entered the land of Canaan. Moses received the law when they left the land of Egypt.
Paul is saying 430 years in Egypt and Canaan, which agrees with the Septuagint.
Pfffft! Since when does mathematical criticism matter?
And Jacob loved Rachel; and said, I will serve thee seven years for Rachel thy younger daughter. And Laban said, It is better that I give her to thee, than that I should give her to another man: abide with me. And Jacob served seven years for Rachel; and they seemed unto him but a few days, for the love he had to her. And Jacob said unto Laban, Give me my wife, for my days are fulfilled, that I may go in unto her. And Laban gathered together all the men of the place, and made a feast. And it came to pass in the evening, that he took Leah his daughter, and brought her to him; and he went in unto her. And Laban gave unto his daughter Leah Zilpah his maid for an handmaid. And it came to pass, that in the morning, behold, it was Leah: and he said to Laban, What is this thou hast done unto me? did not I serve with thee for Rachel? wherefore then hast thou beguiled me? And Laban said, It must not be so done in our country, to give the younger before the firstborn. Fulfil her week, and we will give thee this also for the service which thou shalt serve with me yet seven other years. And Jacob did so, and fulfilled her week: and he gave him Rachel his daughter to wife also. And Laban gave to Rachel his daughter Bilhah his handmaid to be her maid. And he went in also unto Rachel, and he loved also Rachel more than Leah, and served with him yet seven other years.
Genesis 29:18-30