It can happen very fast, or very slow. Nicotine becomes a severe addiction because it gets integrated into your functioning. You smoke to get work done, or to wake up, or to handle stress, and you might start to crave it after you've done that just five times.
Ironically a good rule is to only smoke cigarettes when you've had a few drinks, so your sober mind doesn't realize its potential. At least that seems to work for my brother.
I'm semi-addicted to vaping and chewing nicotine gum. Semi- because I stop every now and then and it doesn't bother me too much, but definitely relying on it to focus. But I used to be prescribed Ritalin, and the side-effects of that were worse, so...