bump it till it pings. every car is different. I have seen some cars take 15* and others knock at 12* just be sure to put premium in it if you advance the timing.
However, if/when I ever get myself into a position where I can stop DD'ing the Pervertible, it's going back up to 12* and getting the premium drinky-drinky, again. I just can't afford premium right now when I'm driving like 350 miles a week (and only getting around 20 MPG average). I'll force my beater DD to settle for the cheap crap ... sort of like feeding the DD ramen noodles and generic soda while the weekend toy gets homemade chicken fettucini alfredo and Mountain Dew.
I'd leave it at 10*, on a stocker there isn't much reason to increase it. That 4-5hp isn't worth the extra cost of fuel, just bump it up at the track when you go.