An ideal list of pointers to consider though some of which I find not very practical. As ideal as it may be to choose a specialty early, you may end up realizing it was never the best fit for you. I often speak of my hopes of entering internal medicine, which in itself is an umbrella for more specialized practices. I leave it broad because too often have I spoken to residents and doctors who tell of how they entered medicine with the expectation of never ever being a gynecologist and ended up loving it.
I think as much as choosing or aiming for a specialty early, it is equally important to keep an open mind because in the fast-paced and ever changing world of medicine, anything can happen.