Yellowhawk,
It's going to take a little bit of time before you start seeing a reliable low end idle setting. Sometimes it can take 15-20 tanks of fuel through an engine before it starts to settle in. Even the best people at tuning an engine will have a high idle on a new engine at times. So what do you do to keep the plane from rolling until you can get the engine broken in? Place a small piece of fuel tubing between the wheel and the wheel collar on each axle. You can adjust the tension on this piece of tubing by sliding the collar in towards the wheel. This will act as a brake to keep the plane from rolling as your engine idles higher. See attached diagram.

Trust me, this isn't a work around. Some planes you literally can't get the engine to idle low enough so the plane won't roll without doing a fix like this. I have a World Models Super Chipmunk that I had to do this to, and my engine is well broke in and idles very low. So don't worry about it.

Ken