As a generality, wait until you are fully trained until you become a kit slut. Then you will have a better idea of what you need or don't. Knee pads seem like a good idea, however you don't want to get ragged on as trying to be an individual. I wore volleyball knee pads all through my basic (TQ1&2, back in the day) but I wore them under my combats, and therefore they were not noticed. If you have a medical condition that requires them, let it be known. If you are talking about urban assaulter style shin and knee protectors, don't even think about it. You will get boarded.
Good luck and enjoy your summer.