Provera for the First Time 🤔

Hello, I was prescribed Provera due to AF being late and possibly having PCOS (my Ultrasound is scheduled for the end of the month to confirm). And I have taken Provera for the 5 days I've been prescribed with and still no AF 😢 I'm 18 days Late. And Not pregnant. How does it work? Would I get AF during taking Provera or After? I'm getting a little concerned