yes, first year med school is too early to make a firm deccision. When you are in third and fourth years, ask to do endocrine electives - this will give you an idea of what the life in endocrine will be like. If you still like it, ask for more electives during your residency. Of course, that goes for any specialty you like.

yea, it's 3 years of itnernal med first, then u apply to endocrine as a fellowship afterwards. I think it is 2 years fellowship--but i am not sure. keep your options open, you will love and hate a lot of your rotations.