In your studies, what mythology in particular speaks of a time before Luna?
There are many tales of a time before the moon, here are a few.
From S. America is the Columbian "Moon Waters" myth:
Many years ago, there lived a man named Bochica........Bochica turned his wife into the moon.
The Humong have a myth :
Long long ago, there was no Moon and no Sun. And there were no people........Then, one day, a man crawled out of the earth from a mountain side.
Morse mythology :
But at last the seas drew back and earth appeared again, green and beautiful. A new Sun and a new Moon appeared in the heavens, one a daughter of Sol and the other a daughter of Mani.
Apollonius of Rhodius :
.......and only the Arcadians lived, of whom it is said that they dwelt on mountains and fed on acorns, before there was a moon.
A Cree legend 'Wesakechak and the Origin of the Moon' begins with:
A long time ago, there was no moon. There was only the sun.
In ancient literature the Pelasgians called themselves Proselenes, because they were there before the moon.