You simply HAVE to build a kit first. If someoe designed and built a full sized plane all by themselves, I would tell them the same thing. Considering the relatively minor time investment of a kit (compared to scratch-build) it would be assinine not to learn all you can from experienced RC designers first by BUILDING ONE OF THEIR PLANES.
Also, you need to get your hands on a trainer, or build your scratch plane to be a trainer or slightly hotter second plane. An "ideal" RC design is low drag, medium-high wing loading, and incorporates flaps and retracts. All things that make the model expensive and harder to fly. All things that make for a terrible first or second plane.
I wouldn't say you're a cocky *******. I would just say your grossly ignorant. Not your fault, and no one should hold it against you. You're only a cocky ******* if you completely disregard experienced advice.
- Josh