I think you could take college classes. There are so many pre-requisites, you wouldn't be enrolled in actual nursing school, unless someone else has other ideas about that. Most school insist on certain classes being out of the way before you are actually enrolled in the Nursing program. Hope that helps!

Most colleges will allow high school students to enroll as long as they go through the paperwork process, typically getting the permission of their high school.  You can be working on the prerequisite courses for nursing programs while still in high school.  Best to get courses like freshman English, algebra, and other general ed courses done first.  Do the science prerequisites last because they usually have a five year time limit on them.  Look at the requirements for different nursing programs that are local to you.  You can find them online or by visiting the campus advising office.  Good luck.