https://www.160drivingacademy.com/truck-driving-classes/cdl-classes/ says you can complete the class in 40hrs. Of course how many hours of experience companies will require to be hired will totally depend on them. So just getting a CDL is not guarantee of getting a job. Getting experience can be expensive with diesel @ $4+ a gallon and the avg. 18 wheeler getting only 6-7 miles per gallon.
From what I've been hearing recently, commercial trucking is a very tough business. With diesel prices at record highs many smaller companies are having a hard time making money. Getting into a larger established company will likely require significant experience.