I was cramping up to 12 after HCG injection. At day 12 you can take a pregnancy test. first response is the one that can detect the pregnancy hormone at the lowest level...I think It  has been 5 years since I did that stuff. Just make sure to look at the box get the one that can detect the smallist ammount of pg hormone. Or go get a blood test....Its such a heartbreaking thing to go to when AF shows up.. on day 12 I was checking to see if I got AF like every 2 hrs. Good luck to you.