6 full turns on the lug nut and you will be fine for daily driving . Just make sure there torqued down . Depending on the wheels your running you might have to trim your studs to run anything below a 20mm bolt on adapter .
I'm surprised that there's good information here. 1.5 is what you should be shooting for. Coincidentally, one of my courses this term has a section based on bolted connections. You might also find this interesting. It shows how the load is distributed on the first several threads. You can see there is a point of diminishing returns.