This is meant with kindness, but honestly as a freshmen there really is no need impo to get the card. They will give you all the uniforms you need as a cadet, minus sneakers, socks and undershirts. BXs vary in size, and not necessarily the cheapest place to buy if you are looking for a sale. Unless you are somewhere with a large BX, I would say no need to get the card until you go to for your summer training. Medically you will not use the base hospital....no need there. Want to travel Space A, you are at the bottom of the list, so hopping is not really practical, especially if you are not by an AMC base.
I live in No VA and have huge bases nearby, but in the last 7 years, my family and I (now retired) have only gone on base 2x for shopping and/or medical reasons. Both times was to purchase items for our DS from the military clothing sales store (Blues and Mess Dress). Don't get me wrong I have gone on base, but it was for things like military balls, and my DSs wedding, something that I would not need a military id, just a pain in the arse if I didn't because I would need to go to the visitor center 1st and checked in.
~ I went so infrequently that my card was expired for 4 years, and only renewed it because DS is an O2 now and he wanted to show his airplane, thus I HAD to renew it. If it was not for that, I would still have an expired ID.