How long should I wait to go to the doctor for chest congestion?

I have been recovery from a cold for almost a week! Friday will mark a week that I will of had this cold. I had a scracthy throat last Friday when I woke up with it. Then Saturday I woke up really stuffed up and kind of a sore throat that lasted till about Monday or Tuesday. Around that same time of Monday or Tuesday I started feeling better in my sinuses and was congested up there but then it started moving to my chest now I cough with no real reason cuz my throat doesn't hurt, although I know its to get the phlegm up! So my question how long should I let my chest congestion go on before I go to the doctor it appeared about Monday (2 days ago) and now I keep coughing. (I am a smoker) although I haven't smoked more than 5 cigarettes in the past 3 days which is good as I smoke about a pack a day usually. but besides that how long should I wait to go to the doctor? I just don't want to end up with pneumonia and have to recover from that!!!