How long does it really take?

How much and for how long would someone have to use heroin to become dependent? School tells me one or two shots is all it takes (bullshit i know).
William Burroughs says one would have to shoot everyday for a month before developing withdrawl symptoms (this seems a little hard to belive too). Could someone with real experience with this tell me what they think?

In a medical setting some people had actual mild withdrawal from just a few days of theraputic morphine usage. (Lower dosage than most use to get high, too.) They recovered quickly, but had some shakiness, anxiety and even some loose stools. Other people in the same study had NO withdrawal in the same period.

People have different amounts of opiate receptors in their bodies. People with more receptors usually have built in tolerance, have less side effects, can tolerate more drug and usually have "addiction" (actually Dependence is a more appropriate word) sooner. (only thing is, you don't know until you are already involved which group you will be in.) Two people could take the same exact amount of an opiate over the same period of time, and one will walk away with dependence and one will simply walk away fine.

two weeks of heavy use gets anybody strung-out.


seen it dozens of times.

...and after you've done the two weeks, 3 days in a row will give you some symptoms.