one slip
I used it recreationally for about 3 months (about 3-4 times a month, generally on a weekend), but it only took a 5 day period when my wife was away (to do with her work), for me to end up in the hell that is being a slave to the drug. I had a couple of months of dependant use before, quite frankly, I became disgusted with myself as I could see the quality of my life nosediving. I cut any connections with the sources of heroin that I knew of (I have friends that sell cannabis and occasionally hallucinogens, but heroin dealers were always "business acquaintences"), and one of my friends helped me out with dihydrocodeine tablets that he had an excess of (he gets a repeat prescription for an injured lower back).
I now know that I like heroin too much for my own good, and haven't gone near it since, but I did recognize that I was going down that route with ketamine, and did something about it before ketamine ended up on my "not to go near again" list
That was my first encounter with drugs that produce a physical addiction, and I know that if I really like a drug with that sort of potential, I have to be very careful in my dealings with it.