Vitex and your ovulation date

Michelle
My last 5 cycles have been between 35-44 days, LP always 12 days. Before that, I took Vitex for one cycle and I ovulated around day 20, and 12 day LP. 
​My question is, did Vitex affect your cycle the first month you took it? If so, how many days did your ovulation change by? I'm asking because I just started using opk's and want to know when I should start testing.