How long will it take to housebreak a year and a half old dog?

My dog is about 1 and a half. i had it almost since it was born, but never bothered to house break it be cause my parents did not want it in the house. I have finally convinced them to housebreak it. My dog is smart, it knows how to sit and lay down but thats basically it. any ideas on how to and how long will it take for it to live in my house without peeing in the floor?