bassman's right, you had that backwards! You do not want a tail heavy plane, and 28 to 30% is leaning towards tail heavy on virtually every trainer I've ever seen.

Put the location of the CG on the underside of the wing where it meets the fuse, pick the plane up and balance it on two fingeer tips (one under each wing). You want the plane to sit level, or very slightly nose down. If it hangs tail down, then shift some weight forward.
Dennis-