Yay! I've heard of practicing by drawing on paper, whiteboards, and kids' Magnadoddle toys, but I've never heard of tracing over it with the machine unthreaded. It sounds like a good idea.
Good luck with your machine. I, too, quilt with a Janome Artistic, the 18 inch model. When I get the opportunity I think I want to upgrade to a bigger throat. Last week I got to attend the Machine Quilting Today show in Wisconsin and tried lots of different machines. I've only been at it for a year but I've discovered that I love longarming!
Have fun!