...how do people make a case for the first 3 days to be literal 24 hour days...?


Here is a case by which I believe that w/out a doubt the Genesis creation account is referring to litiral days as opposed to "ages" (day and age in Hebrew is the same word).

Exod 20:8-x

"Remember the Sabbath day, to keep i holy. Six days you shall labor and do all your work, but the seventh day is the Sabbath... 11. For in six days the LORD made the heavens and the earth, the sea, and all that is in them, and rested the seventh day.


1. I think, here, need not be an argument that the Sabbath day is a literal 24 hr period.
2. In instituting this literal 24 hr period God refers to Genesis creation account as an allegory for justification:
If I, God, considered this day important enough to rest on it, how more so shall you!?
3. The argument, therefore, would fail if the word "day" in creation account was referring to an ambiguous age.