I've been in vitex for about 26 days now and FF says I ovulated on CD22. I'm on CD25 now, so with any luck it will shorten my cycle to about 36 days this month, which I'd consider a win for now! Of course, it'd be better if I was pregnant 😄
As for dosage, I take an oral spray that is equivalent to about 500g daily, too. I've heard that people taking it for fertility take 1000-1200g per day, but I'm just sticking with the dose my naturopath gave me for now. I'd be nervous to take too much as I think you're meant to wean off it once you're pregnant, and dropping down from such a high dose might be problematic.
Anyway, I think it takes a few months to really make a difference, so good luck to you too! I know it's tough when you just want it now! 😉
Sorry for the essay!