I would not recommend that smokers hold their breath waiting for this. There are a number of very good tools available to help, so go with those now. The heart is the organ that sees improvement within minutes. The pulse and blood pressure come down, and we think your risk of a heart attack goes down - not to normal, but it goes down some right away. However, there are also some very unpleasant changes that happen in the short run that are caused by withdrawal of nicotine from your brain.
People can get shaky, irritable, have trouble sleeping and concentrating.
To expand - there is absolutely no other product in the world that, when used as directed, will kill one out of three of the people that use it. It is true that most smokers who quit gain some weight. Probably about 4-6 pounds of this gain can be explained as due to chemical changes in the brain as the body gets used to not having nicotine around. It's much much much better to gain five pounds than it is to keep smoking. Well, there is good news and there is bad news.