It's kind of controversial, some people love it, some people hate it. I'm not a big fan, never had good results. I just figure that since its your first grow, let it go naturally and see what it does/looks like without much interference. I don't trim the bottom branches either unless they will be hanging into damp undergrowth and most likely rotting. The sunlight has already traveled 93 million miles to get here, another 7 feet to the bottom of your plant is nothing. The lower branches also serve as insurance in a bad Autumn. If my big top buds all go moldy during a rainy harvest, there are always smaller bottom buds which won't rot as easily.