I believe the method suggested to you is in error and will result in a CG being too far BACK. The CG you show with the stick is not far enough forward. I know there are posts on this news group which will show the correct method so I suggest doing a search for "determine cg" or "find MAC" (Mean aerodynamic chord).
In the meantime, I suspect a more informed ng member than I will have the link for you before the day is over.
The model looks good, by the way.
Allan