roughly 9-12 years
The distance from Earth to Pluto is on average 5.85 billion km. Pluto travels around a highly elliptical orbit around . At its closest point, known as “perihelion”, Pluto is only 4.4 billion kilometers out. At its most distant point, known as “aphelion”, Pluto reaches a distance of 7.3 billion kilometers from .
Depending on when you are starting your journey from Earth, and the Pluto’s position in its orbit at the time, one can calculate how long its going to take to get there.
http://www.universetoday.com/119264/how-long-does-it-take-to-get-to-pluto/the link is for further reference
hope this helps :))