Special Forces Candidates (18X) will attend Infantry One Station Unit Training (OSUT), which combines Army Basic Combat Training (BCT) and Infantry Advanced Individual Training (AIT), in one 15 week course at Fort Benning, GA. Upon graduation, Special Forces Candidates will attend 3-week Airborne Training also at Fort Benning, GA. After "jump school," candidates attend a 3-week Special Forces Preparation and Conditioning course (SFPC) and then the 3-week Special Forces Assessment and Selection (SFAS) program at Fort Bragg, NC. The SFAS program assesses and selects Soldiers for attendance to the Special Forces Qualification Course (SFQC).
SFAS course uses a “Whole Man” selection process that assesses each candidate for six attributes that are important for all Special Forces Soldiers. These attributes are intelligence, trainability, physical fitness, motivation, influence, and judgment. If the recruit passes SFAS, he moves onto the SFQC. The SFQC teaches and develops the skills necessary for effective utilization of the SF Soldier.
There are four entry-level Special Forces MOS (CMF 18) .The decision of which SF MOS and language you will be trained in is based on your background, aptitude scores and desire. But, ultimately it will be up to the needs of Special Forces.
As to whether you will have to attend BCT before Infantry is up in the air. You will need to talk with a regular Army recruiter. Most likely you would not and just go straight to Infanty-11B training (4 weeks)