The easiest answer: Measure 1/4 of the wing at the root from leading edge and hold the plane at this position. If it's level, fore and aft, it's OK to fly. If it's "squirrly" flying level, then it's tail-heavy. If it's hard to change direction on square loops, then it's nose-heavy.
Hardly any plane flies perfectly balanced the first flight. Adjust the CG until it gets where you like it.
Floyd