evening primrose oil

Leah • Pregnant with #2
I'm due tomorrow and just had a doctor's appointment where I was told I'm 1/2 a centimeter dilated but other than that my cervix isn't ripening yet. He suggested evening primrose oil. Have any of you had success with it? If so, how did you take it (orally, vaginally, or both) and what dosage did you use? So frustrated! Tomorrow not only my due date but also my bday, and I was really hoping to get to meet my baby girl. I feel like she's never coming out!