I'm still trying to get some of mine to turn green. I have sample packs of both PG and VG and use them for dripping. I intentionally pumped air into them from the droppers although I doubt that is the cause. It's not possible to remove liquid from any suppliers bottle without it being replaced by air.
Just under a month now and no love on the green yet.
I still have all my samples of both nonpg and pg from January 20th and nothing is green. Only one that changed color was the vanilla ice cream, it looks a bit darker then it did when I 1st opened it.