Training required to become a pharmacy technician?

Hello, I am going into my junior year of college and thinking about becoming a pharmacist. I figure that in addition to getting good grades and a good test score on the standardized test, a job as a pharmacy technician on the side is always a plus to get into pharmacy school. I was thinking of applying to a Walgreens or CVS because I read that they train you on the job. How long does the process of training take? I only have 2 months of summer so I figure it is too late now. But when I go back to school I was thinking of applying at the local CVS there. There is about 4 months in a school semester. Is that enough time? Or should I just concentrate on studying instead? (I am switching majors from a different field midway through college, so I still need to take all the prerequisites to get into pharmacy school)