Its worth taking time to get the C of G right, better this than walking home with a bag of bits.
Make sure your method of balancing the model is accurate.
Finger ends under the wings is not good enough, you can easily be 10mm out.
Be accurate and mark or record the measurement.
Start off slightly nose heavy,...thats better than tail heavy. You can then adjust a bit at a time until you personally are happy with it. Dont follow someone elses advice who says " put it 20mm further back" It may be ok for them but not for you. It may take a dozen flights to get it right but who cares if it ends up right.
Last thing if you have computer radio, set the dual rates up so at least you have a chance at the flick of a switch if the Cof G is a bit out