How Long Until Results Are Back?

I had to go in for serial HCG testing, and yesterday was my second blood draw. They said they would call me with the results, but they also said that the first time and they did not. I was wondering how long I should wait before I contact them and ask for my results if I don't hear back. I'm very anxious and trying to keep a positive mindset, but I just want to know if my baby is growing.

*UPDATE*

I got a call back from my doctor an hour after I posted this. I have an appointment on the 26th for a follow up ultrasound to see if anything has changed. Hopefully everything goes well