Musar zu Bereschit 11:30

The second "day" followed later when G–d told Abraham to go to the land of Israel. This represented the fulfilment of the first part of G–d's promise. The extra letter ה in the description of יום הששי, refers to the day when Israel accepted the Torah at Mount Sinai.We are told in Avodah Zarah 9 that the two thousand years of "Torah" commence with the time that the Torah mentions Abraham and Sarah as having succeeded in converting people to monotheism, i.e. ואת הנפש אשר עשו בחרן (Genesis 12,5). [The foregoing is based on the tradition that mankind prior to the Messiah experiences three periods of 2000 years, the first period described as "Tohu," the second as "Torah," and the last as "days of the approach of the Messiah." Ed.] Abraham and Sarah respectively had proselytized, he the men and she the women. Abraham was 52 years old at that time.