primrose oil / olive oil / coconut oil

Hey beauties ! I'm 28 weeks & 5 days pregnant with my first baby and I was wanting to know your advice for when to start taking "primrose oil " to prevent tearing during birth and If you also apply olive or coconut oil? Can you use both? I have absolutely no idea but have seen this popping around and what to at least take any preventive steps and at least know I tried lol