It's been 20 yrs since I quit so it's hard to remember, but I think it was 6-8 months before I got over wanting a cig at those "habit" times--on the phone, at the computer, driving, etc. The last craving to go was smelling someone light up--that first sniff of a freshly lit cigarette. That was longer but I don't remember how long.
Definitely worth it tho for me.