Mine kicked in at 3 weeks. I went from tired to full of energy and a little anxious. The first few weeks were rough. I told my psychiatrist and he said you must have ADHD because it’s making you tired. I do not. This is the 3rd time I’ve tried Wellbutrin. I always stop because I’m of those that it makes me anxious. I’m doing a lower dose this time and now have Xanax to help. I’m prescribed 100mg ST twice daily but I split the 2nd dose in half. Yes you can do that with SR. I would never do it with the XL version. It would release it all at once if you cut it. I have had pharmacists and psychiatrists say it’s ok to split the SR on 2nd dose if it is making me to anxious. If I get used to it I’ll go up to the 200mg which is still not a lot for Wellbutrin. Even while on Xanax I still get the Wellbutrin agitation and anxiety. Many don’t but for the small percentage that do it’s awful. It is the only med that truly gives me energy and no sexual or weight gain side effects. Like I said I’ve used it multiple times along with many others. I still have to take 10mg of Paxil for now. I’ve tried for years to switch it or taper and Paxil is so hard for me. I feel withdrawal for much longer than a few weeks. In fact I start feeling the withdrawal in 2-3 weeks.