DCD,
Definitely an intelligent approach to learning this hobby, but give in a bit more to the compulsion side of it. Buy an ARF now too!

Whether or not your son maintains an interest, and I'm guessing he will, you seem as though you WILL remain interested, so indulge yourself.

Putting the ARF together (as a first timer) will take approximately 25 to 40 hours, so if you spend 2 to 3 hours per week with your son assisting, half your winter will be spent getting it ready. A RTF on the other hand is only a long Saturday afternoon.

In any case, welcome!, and have fun.
Dennis-