I use the glow plug that comes with the engine for break in and then put in an OS 8 when I am ready to fly. I never fly with the break in plug.

I don't really look for a good idle until it has flown a few times, and gotten good and hot with full throttle runs. I guess I settle for something around 2600 at first. When I break in this .82 I'll set the needle valves the best I can before putting in on a plane. Then, I'll check it again before flying. Things change going from test stand to plane. I'll probably put an hour on the engine before taking if off the stand and I'll give it more full throttle runs than my last ones.