10 years, besides 2 1/2 years of aftercare following addiction. (During aftercare, five of the participants died from overdose. Scarry to watch.) In all that time, I never can remember an individual under 25 being able to stay clean. They would get six months, proclaim they were cured, then ... relapse.
The timeline presented above seems realistic in my experience.
The Twelve Steps are miraculous. I am a great believer in AA in tandem with the Church's ARP program ... Just wish more members would take advantage of ARP. Time, determination and God's grace are key to recovery.