The CG that is given on the plans is really just a starting point. The actual range of the CG is usually pretty variable, depending on your flying skill and style. But there are definite limits. Too tail heavy, and it will be really pitch sensitive, or not flyable at all. Too nose heavy, and it will be hard to take off and sluggish. If you must guess at the CG, it's better to be a little nose heavy, than tail heavy, especially on a trainer's first flight. After that, you can adjust it to suit your flying style.

Jesse