Short answer: Your CG should be set using "dry weight" as long as your tank is at or forward of the center of gravity.

Long answer: Ideally, your CG should not change between a full and an empty tank. If you use a "header tank" -- a small tank in the nose -- and some stiff fuel tubing back to a fuel tank located near the CG, your CG will change much less than if you have the traditional "fuel tank near the nose" approach. However, if your ARF isn't designed that way, it's tougher to relocate the tank.

And, of course, if flying an electric, as there is no shift in CG, you should get your CG perfect with the battery pack installed as it represents such a substantial chunk of the overall weight of the aircraft.

Thanks. It is as I thought.
Jim

The CG does change with the tank full but the fuel just adds nose weight.

Here is the worry: as you burn fuel you don't want the plane to become tail heavy. So you check with the tank empty to make sure that with zero fuel the plane didn't become tail heavy.

Then when you fuel the plane it becomes nose heavy - that's normal.