One of our USNA sponsor mids graduated in top 20 of his class, worked very hard as a SWO to become the top-ranked JO on his ship, was the collateral duty Legal Officer on his ship and spent leave periods shadowing JAGs at the base legal office. He got in on his first try, after being accepted to a well-known law school. It was extremely competitive, and he has carved out a successful career. He often notes he would not trade his time at sea as a line officer for anything, and his SWO pin earns him instant respect from the commanding officers he works with. He’s been there. He also didn’t walk into his first ship and say “I wanna go JAG.” He put his head down and worked to become the best SWO he could be. Only a small handful are able to do this lateral transfer every year.
It is good to have short, mid and long-term goals, but also to be flexible. Presumably you researched career paths prior to applying to USNA. You are there to learn to become a warfare line officer. Be open to all paths. Your job right now is to be a good Plebe, then a good mid, and make thoughtful decisions about taking on the service obligation 2/c year and then deciding on your warfare community. Be the best you can be wherever you are and whatever you are doing, and doors will open.