When to start progesterone

Natalie • July 21 💚 Feb ’20 💙 March ‘18 💙 Dec ‘15 💙🧩 4 miscarriages 🌈
For those with low progesterone, when did you start taking supplements for it?  My dr prescribed pill form to take after my next BFP, but I've read online to start taking a few days after ovulation.  How many days after ovulation, exactly?  Seems like progesterone would be helpful now, especially bc my temps are slow to rise.