My hard numbers (if you mean location in inches) will be 3 and 1/2 to 3 and 3/4".
My intention is to fly straight IMAC areobatics. Tom recommends a CG location
that will make the first flight safer with a more fwd CG, in my opinion. My next step
is to balance the airplane so when I do a 45 degree upline, roll the plane on it's back.
and if it continues straight up 45 degrees, it's balanced for how I need it, and I don't
care where the CG is actually located.
Others will tell you that they prefer the CG further back for 3D flying, and they all do
not follow a uniform number.
Therefore, figure out what you want to do with the plane, and decide where the CG
would best be located for that type of flying. Batteries and rudder servo(s) are best
installed last, to allow adjustsments as necessary.

Gerald