My honest take on this is that you should build your first trainer. The reason is that when you advance more you'll need the skills you learn from previous building experience. A trainer is tolerant of building errors, but a more advanced plane isn't.

You'll get to the point where you can tell the difference between a straight plane and one that isn't.

If you wait to build until you get to the point where you're flying these kinds of planes, then you'll be behind the curve. Also, even if you fly nothing but ARF's, it still helps to know how to build a plane for times when you need to make repairs.

- Paul