There are Round Circles on the plans for the CG.
My recommendation is and always has been to put a strip of velcro down the underside (or side) and velcro on the batteries so that you can adjust it at first to get close to that CG point. Then run a BBQ skewer through and use a Velcro / Rubber Band Combo.
Slightly nose heavy is better than neutral or any tail heavy. (Unless it's a 3D plane....)