Actually, it takes around 2-5 years of solid police work in order to become part of a specific unit (K9, Homicide, Gang ect..) So first your college degree (since most police departments will only hire if you have a college degree) then police academy, then your 2 -5 years of police work.. Then you can become part of a specific unit.
4 years maybe, going to college, the training to become a cop, and then training with the k9.
It takes five years
I t requires a good amount of time and patience. 3 years or four years maybe.