How quick can wellbutrin work for quitting smoking?

I've been smoking for a few years now. I went to the doc on friday w/bronchitis. I told her I needed to quit smoking because of getting bronchitis so often. I told her I was afraid of anxiety so she prescribed wellbutrin and told me to take it in the mornings. Satrday I started it. I only smoked 5 cigs, sunday 3, yestrday 3 and today 1. I didn't know how it was going to help quit smoking . Could it be workig this quick?? I def feel nicotine withdrawal symptoms..I don't think the meds have had time to work but how is smoking making me nauseous all of a sudden?