How long does it take to quit smoking after 2 years?

Depends upon the person.  My husband tried to quit for the first time after he'd been smoking maybe 2-3 years.  All told it took around 20 years to quit.  We moved north and he wasn't allowed to smoke in the house or the office.  Having to huddle outside when the wind chill was below zero for a few years finally did the trick.  That and one of his smoking buddies being put on the waiting list for a double lung transplant.