At the risk of being redundant, I suggest this:

If the recommended location of the airplane's CG is unknown, use the calculator provided further up in this thread. It looks complex, but MAC is not meaningful if the wing is straight and square. The neutral point they refer to is the center of lift. For models you always want your CG a little ahead of the NP.

I checked a "Hershey Bar" wing shape and it suggests a CG point located roughly 30% of the wing chord (width, NOT SPAN) back from the leading edge. The 30% rule of thumb is a good starting point for any straight square wing. Swept and tapered wings are a little more complex and the MAC (Mean Average Chord) becomes important.

After locating the required CG, test your plane by balancing on your fingertips as described farther up. Move stuff around or add weight until it balances WITH AN EMPTY FUEL TANK. You want to end up good on an empty tank rather than start in balance and get tail-heavy at the end of a flight.

Always re-balance used airplanes you buy, and after repairs or engine changes. Even small repairs to the nose or tail can dramatically change the balance point. Best of luck.

N