Get the book "Easy Way to Quit Smoking" by Allen Carr. I've quit 2 times because of this book. So MANY people swear by it. It gives you the right frame of mind, totally changes how you look at the "habit". The author smoked 100+ a DAY (yep, you read that right -- over ONE HUNDRED cigarettes a day). Can you imagine?!??!?!
As for time, cravings, what to expect - it's so different for everyone. To tell you it's only a few days - makes you anxious to get through "those few days". To tell you it's weeks, months may only scare you. So I will suggest what I did and it seems to be working and working well.

I read the book, set my quit date while reading the book, and gave myself a goal of 24 hours. Got me a little quit meter thingie for the computer and watched it like a hawk. Once I got through that 24 hours (which was much easier than I expected) - I did the same the next day and so on. I celebrated each minute, hour, day that passed.
I am now working on my 3rd. week (cold turkey) and it seems like longer, not because is has been a battle but because I actually forget about smoking and I have to check my meter to actually see what day I'm on. *weird*
You can DO IT!!! Trust me!!! It's scary!! I firmly believe making the COMMITMENT (setting a date) to quit is harder than quitting!!! Once you make that resolve, in your mind to quit, you've gotten over the biggest hurdle.
Good luck, keep coming here! These are some truly wonderful people! And if you get the urge to smoke, once you quit, POST FIRST! Yell for help!
Keep us updated.........................