Yes craft, the benefits of stopping smoking are felt within 20 minutes:
http://healthyliving.msn.com/diseases/quit-smoking/quit-smoking-6
In the time it takes you to read the morning paper, your health can improve significantly when you stop smoking. "The overall health impact on the heart when you quit is dramatic and fairly quick," says Lichtenfeld. It takes just 20 minutes for your heart rate and blood pressure to drop, and less than a day for the carbon monoxide poisoning in your body that comes from cigarettes to dissipate.
After three months, your circulation will improve and your lungs will be working more efficiently. "When you smoke, there is an immediate reaction to your heart rate and blood pressure," says Lichtenfeld. "Lung function gets better within two weeks to three months after you stop quitting, but the improvements to the heart can be immediate. Smoking puts toxins in your body that affect the way the heart works, the blood vessels work, the organs work. And when you remove that toxin, that allows the body to start healing right away."