The timeline can be found on the internet. I dont recall it, so wont offer it. I would suggest a nutrionist, because no one knows you, and not sure how much to recommend.
I am not sure if you already have lung issues? If you do, stop smoking will improve areas that effect the lungs. If you have been diagnosed with damage, you can still have some degree of healing. I know I am evasive, but any information I could give you could prove to be as deadly as the cigs. See a good nutrionist.
Also, you might want to do some reading on biology of the mind. There are excellent books now, on how people are healing themselves. I am one who is doing such with success. check out you tube Bruce Liption and Jill Boyte Taylor. Listen to what they have to say, and if you want you can order their books or go to the bookstore or library. There are others too you might wish to listen you, this is not a limited list.
Best of luck to you.
I been smoked free for 3 yrs. Best choice I made. The benefits outweight smoking in a heart beat.