Honestly do it really make a difference, if you legalise it one place and people see it doesn't end up with God going all Sodom and Gomorrah on that place (or the state forcing all people into gay marriages), people tend to be more willing to legalise it other places too.
I have no clue what you are trying to say. Could you explain?
Lot of people who are somewhat hostile toward SSM tend to become lukewarm supporters, when they discover that the adoption of SSM elsewhere haven't had disasterous effects.