Do you go to college, then B.L.E.T( Basic Law Enforcement Training)

Most law enforcement agencies will send you through their own basic training.

In general, you're not required to complete your college degree prior to attending a law enforcement training academy. However, it becomes more difficult to complete while working full time or other changes in your life. I completed my bachelors degree after being hired, working full time. Later, i completed my masters degree while married, one child and a pregnant wife and working full time. It can be done, but it becomes more difficult.
While completing your college degree (before hand) you can possibly do an internship with a law enforcement or related criminal justice agency. I did an internship with a Juvenile Justice Advisory Committee while in college.

As a side note - i'd recommend a degree in public administration, it would broaden your career options later in life. Nothing wrong with criminal justice degrees but it won't generally make you a better officer. Explore psychology, sociology and electives that while give you a better understanding of the community you will be serving. Best of luck.