I have been on several different meds for depression, and I also felt some immediate differences even though it takes awhile to get the full effect. Wellbutrin works on different brain chemicals than most of the other meds, and can have a stimulant effect (which is the opposite of most), which is why they say that this one causes the least weight gain. This may be why you are feeling agitated and angry. I had the same issues. Most people have to try several different things before finding the right medicine. This one had the mildest effect on my depression, however, but also had no withdrawal symptoms for me when I stopped taking it. I would mention it to your doctor, because if you are feeling angry and it is out of character for you, then it probably is the stimulant effect of the Wellbutrin. If you can deal with it, try to see if it starts working better after time, but if not, there are many other things out there. Discuss it with your doctor so you can make educated decisions about your health.
I'm pretty sure the first day that you took it has nothing to do with the med at all. It takes, like other posters have mentioned, 6-8 weeks. From what I know you have to be in the 300mgs range to be helpful for smoking cessation, but they've done a couple of studies, saying it was only a 20% success rate taking this med. I wouldn't hold you breath on it. I have noticed a small decrease in cravings, but it could be just me being more careful.
I used to take Wellbutrin and for me it was great for depression but totally aggravated my anxiety. I took xanax with it to take the edge off. I felt the side effects right away, and felt better within about a week or two of starting it. I liked Wellbutrin because I didn't gain weight. In fact it decreased my appetite and it didn't make me feel sluggish or zoned out like other meds I had tried. It also had the lowest side effects for me. But the agitation is standard from what I've heard from others using Wellbutrin. Good luck and feel free to email me with any questions, I'll try to help if I can.
Most side effects go away with time.
It takes 8 weeks to get the maximum effect because the drug builds in your brain, so you need to give it the full trial if you want to see if it works. However if the side effects are unbearable see your doc and she might change your prescription.
I don't know if those effects you mention could have come from the first day of use though. You should talk to your pharmacist about the effects if you don't have time to see your doc. I recommend talking to your pharmacist whenever you have a question, while on SSRI, because it is very easy to worry needlessly and discussion can resolve the worry.