I am a college student who made it to the class of 2023.
Just like everyone has said, the application process is really similar. And as USMA 1994 said, they don't review until they have gotten your first semester/ quarter of college transcripts in.
Nominations are still really important. They will be the same as a high school application, but you will need to provide a college transcript. If you are unable to provide those by the time of the interview, probably because the term hasn't ended, contact the congressional staffers about what should be done. The interview may include questions like, "Why didn't you apply in high school?" and, "What have you been doing in college to prepare you for the Academy?".
Another difference is the college activities submitted on the supplemental information sheet. This is similar to the Candidate Activites Record that high school students fill out and have verified by a high school counselor. The difference between the two is that the college activities form is a blank text box that you can put anything on. It also doesn't need to be verified by a counselor or school official.
If you are a first-year college student you are allowed to ask senior year high school teachers for your recommendations. If you are a second-year college student, you will only be able to ask college professors. If you are a previous applicant, previous recommendations are kept and carried over to the current application, including high school recommendations. You can, of course, remove old ones, but at least two old recommendations are required.
I have heard from a Naval Academy blue and gold officer that the Naval Academy cares more about grades now that you are in college. That might be true for Military Academy as well.
Stay involved with sports, activities, and employment. Take on leadership roles, but don't forget to also show that you are capable of teamwork.
Make sure to get close with professors. In high school, there were many chances to talk with the teacher and the opportunity for a closer connection. Whereas in college, it is much easier to never interact with a professor, and never make a solid connection for a recommendation. Make connections with professors now so that you have options for people to fill out recommendations later.
Be careful of the recommended courses for college students. West Point recommends that you take classes similar to a plebe, but as a second year California Community College mechanical engineering student, I encountered a big problem. This last semester was filled with all of the STEM courses that I didn't take my first year. It was a really challenging semester, and it didn't have to be that way. It should also be noted that had I failed to make it into West Point, I would have been unable to transfer to >80% of my in-state universities because I didn't take all of the required courses for transfer in my major. tl;dr-- Be careful, visit a school counselor and spend some time thinking about what courses you should take.
Other than that, the application is the same. Do your best to improve all parts of the application: grades, course-load rigor, sports, leadership roles, teamwork activities ( clubs and extracurriculars), standardized test scores, CFA scores, essays, recommendations, employment, etc.