vitex experience

I usually have a 35 day cycle, I decided taking vitex bec I wanted to have a 28 day cycle like when i was in bcp. so last Nov 23 i started taking it and after 12 days I already had my period (last period Nov.8) so did the vitex do the job? did it really help me to have a 28 day cycle. Did it work that fast? Now that I have my period I stop taking it ( 5 day rest) but I really don’t know if i will retake it again because honestly I am also afraid that this is just a mid cycle bleeding( never happen to me). I’ve read a lot of stories abt this when they started taking vitex.I’m really confuse.. any advise please, thank you