Paul summarized his point in Galatians 3:17. [source][source][source]
The430 years probably began with God"s reiterating the promises to Jacob at Beersheba as he left Canaan to settle in Egypt (in1875 B.C.; Genesis 46:2-4). They probably ended with the giving of the Mosaic Law (in1446 B.C.; Exodus 19). [source][source][source][source]
The "inheritance" ( Galatians 3:18; cf. Galatians 3:29; Galatians 4:1; Galatians 4:7; Galatians 5:21) refers to what God promised to Abraham and his descendants, including justification by faith implicit in blessing. Reception of this did not depend on obedience to the Law, but God guaranteed to provide it. The idea of inheritance dominates much of the discussion in the following chapters. [1][source]
". . . the inheritance of Galatians 3:18; Galatians 4:30 is parallel not with the land promises, Canaan, but with the gift of justification to the Gentiles. This is the major passage in the New Testament used to equate the inheritance of the land of Canaan with heaven, but the land of Canaan is not even the subject of the passage!" [2][source]