I found mine just after 9 weeks. Although at first I could only find it in the evenings and not during the day/morning, and my friend said the same. Since I have only been using it at night as it was getting me in such a state.
I found mine pretty much straight down from my belly button but maybe just a little bit to the right.
Please dont panic if you cant find it one evening though. I got myself in such a panic the other day as I was trying at the same time as usual and just couldnt find it. I was trying on and off for a couple of hours and oculdnt find anything. I was in such a state and was really worried. Luckily I did finally find it and it was lovely and strong.
As others have said, bubba is still so small and has such a big area to move around in. It has to be in exactly the right place to be able to hear it. Also when i find it bubba is usually being hyperactive and moving alot so can only hear for a few seconds at a time before I loose it again.
Good luck xxx