I've been on 1200 mg/day for years. I also noticed some benefit early, within the first week, but had increasing improvement over time. For example, lithium is one of very few drugs known to reduce suicidality, something I struggle with. I think it has done this for me for the most part, but it took awhile to fully kick in. It is by far the best drug I've ever taken for bipolar disorder. I hope it helps you.