Tsuwm, I’ve never heard of "avant verrais."

It’s a rather confusion structure of words.

Avant means previous or before.
Verrais is in the “Conditionnel present” form – which means it says “I would see if…”

Are you sure there was an “s” at the end of verrais? If it was simply avant verrai, though ungainly, it would mean "before seeing."