As others have said it varies greatly by individual.
But perhaps the more important point is that physical dependence is not even the thing to be scared of. What you need to worry about is psychological cravings, as this is what leads you into addiction.
Physical dependence is really just an inconvenience in the grand scheme of things. The psychological side of addiction, cravings, etc is what does you the real harm and this often take a long time to go away if it ever does fully disappear at all.
You ask anyone who has been clean from H for years, most of them will tell you they still struggle with cravings. That's the real monster you have to beat right there.