I haven't had physical cravings or mental obsessions about drinking since I got sober. They seem to have gone away almost immediately once I surrendered to the fact that I cannot drink like a normal person. The physical craving was gone within days of my last drink, the mental obsession within a week or so.
I have no doubt, however, that if I had one drink, I would soon be craving more--I wouldn't be able to just have one now and then. I would soon be back to my old pattern of drinking as long as I could, each time, and obsessing about not running out, topping off my drinks when the ice melted, etc. The physical craving and mental obsession seem to go together for me.
From what I hear from many relapsers, though, they didn't feel they were obsessing or craving until they carelessly had a drink and then they were off to the races.