personally I would have the radio on hand. I made a mistake with my first build by getting the kit, then the engine, then the radio. There was a good long lag between each purchases. A few parts from the kit got lost (my bad... but when u have it around for a while it can happen) and I atleast find it extreamly hard to pick back up a project half way through after a length of time. The kit never got finished. I bought a new one recently and have started to a rebuild on it. I could habve just gotten the missing parts, but I was unhappy with having built the wing with more dihedral anyways, so I just got a new kit and bipassed the starting half way through. Anyways, that's just my opinion.
-John