Pb, it depends on your doctor. For me, once I get bfp, they will do beta checks every few days to make sure they are doubling. The numbers should double every 2-3 days, Then - once your numbers are over 1000, they "should" be able to see something on the Ultrasound. Even if its just the sac and fetal pole. It all depends on your doctor though.
Some will do one blood test and then tell you to come back when you are 8 weeks. For me, I will be monitored closely as I have the risk for ectopic, so it really all depends.
Hopefully, your doctor will have you go in for bloodwork right away, then whatever you beta number is, they will have you come back in a few days to make sure its going up. Then from there, they will decide when they want you to come back for an ultrasound.
Im so excited for you! Did you call your doctor yet? I can't remember, are you seeing an RE or an OB"?