Nobody in ancient times could have imagined that the earth was
billions of years old, so you won't see any explicit attempts to
reconcile the Genesis creation stories with an old earth.
However, the early Christians did see discrepancies that made
them question how literally the creation stories should be
understood. Second century Christian apologist Justin Martyr
wrote in his Dialogue with Trypho, chapter LXXXI: For as Adam
was told that in the day he ate of the tree he would die, we
know that he did not complete a thousand years. We have
perceived, moreover, that the expression, 'The day of the Lord
is as a thousand years,' is connected with this subject. You can
see already the seed of the notion that the "days" of Genesis 1
do not refer to 24-hour periods. Third century scholar Origen of
Alexandria went further in De Principiis IV.16 [emphasis mine]:
For who that has understanding will suppose that the first, and
second, and third day, and the evening and the morning, existed
without a sun, and moon, and