Army rangers??? How long should it take?

So for those that are coming from my question about being a medic in the army thanks for stopping by to help me on this other question...I want to be a medic in the army but not just the regular army I wanna be apart of the rangers. Either the 75th or 1st battalion is fine but how long would it take for me to be able to do that? uming that I'm coming straight out of college with a BS in nursing. After basic and AIT. Is it even possible for me to go straight to a ranger regiment??? Or would I have to be in the army for some time? If so how long? And lastly, how much training would i have to go through to become a medic with the rangers? Thanks :]