The premed program at SGU is 3 years in total.Each year is divided into 2 semesters(i.e Year 1-1,1-2,2-1,2-2,3-1,3-2) and at the end of the 3 years you take the pmsce(I think it's the premedical sciences comprehensive exam or something) which covers the the courses you take in year 3.
When I was in premed,you had to maintain a gpa of 3.2 or above and pass the pmsce in order to enter the full medical program at SGUSOM.If you had a gpa between 3.0 and 3.2 and you passed the pmsce,you were placed into the alternate program of medicine.
Now how long it takes also depends whether you fail a course,or do or do not meet other promotion criteria for entry into the medical program(or even the veterinary program also at SGU).
If you opt to do a Bachelors Degree(BSc) from SGU,it is 4 years.Which comprises the 3 years of premed and the first year of basic sciences at SGU.
A valuable source of information is the SGU student handbook or email the school for further information.