Evening Primrose for irritablity.....Im 38 wks preg. ?

I want to know if i should wait to start taking until ive had my baby? I would be taking it to improve my mood swings, anger, irritablity, i have no patientce. Ive been like this for yrs. Just is getting worse. Im married, i have a 4 yr old with autism, im a SAHM, and having a c section on July 7th......