From when to when does the 430-year period in Genesis count?
The 430-year period counts from God's call and promise to Abraham to go to Canaan until Israel would come out of Egypt as a nation. God delineated that span as 430 years, with the sojourn in Egypt beginning at its midpoint, 215 years after Abraham's call.
Les teaches that the 430-year period begins with God's promise to Abraham at His call to go to a land He would show him, which was Canaan, and runs until Israel would be a nation coming out of Egypt. God delineated this as exactly 430 years. The midpoint of that period marks the beginning of Israel's sojourn in Egypt, so 215 years elapsed before the Egyptian sojourn even began. This corrects the common impression that the Israelites were in slavery and bondage for the whole 400 years.