Don't expect to hear it straight away - I was 13 weeks when I got mine (the angelsounds one) and thought I'd hear it first time after reading so many people finding it much earlier. After a few failed attempts over the course of a few days, I decided to give up on it for a while, as it was just making me fret!
Tried it again this morning as I was lying in bed feeling sorry for myself with a rotten cold, and got it straight away!
Thundering away like a galloping horsey!
Just above your pubic bone is where you need to listen - you need to press down quite hard and use plenty of gel as it really does make a difference. I hope you do hear it first time, I just wanted to reassure you in case you don't though. Happy babba hunting!