I am in the process now. I am also prior enlisted and just got selected for 66H (although my numbers may be off on the weeks). If you apply to a direct commission, you will not be going to an officer candidate school (OCS). However, you will attend the direct commission course in Fort Sill. This is 4 weeks long. Then you will go to Ft Sam, Houston where you will attend the basic officer leadership course (BOLC). I believe it is 7 weeks with 2 weeks being nursing specific.