Open Question: How long doe it take to go through a twelve step programme properly the first time?

I realise that it is a lifelong attitude of using it for the rest of your life, but I have met a man who is in recovery from a narcotic addiction (primarily cocaine) – he’s just got his 90 day chip from NA, but i want him to go through the 12 step at least once before I would consider getting into a relationship, and I need to know what sort of time frame I should be looking at? Three weeks? six months? two years? I’d love to hear from people who have been through this?