If your goal is to be a NP, I would recommend you switch majors ASAP so that you can begin to focus on nursing. College is expensive and experience as a nurse is important when looking for a job as a new NP. Bio majors don't have a lot of options when it comes to making a dent on their school loans before heading to grad school, while nurses usually start at double the minimum wage. Also, if you change your mind and want to go to med school, optometry school, or any other healthcare related field after you graduate, you would only have to take a handful of prereqs to be ready to take the MCATs etc. Hence, a nursing degree gives you more options as well as focus, if you do end up becoming a NP.