Hello
I'm currently on my 4th stint of fluoxetine in just over 10 years. The first 3 times i started to feel better after about 2 weeks and didn't have any side effects but this time it was much different. I could feel my depression coming on (i've got used to spotting the signs now) so jumped on the prozac sharpish (20mg). For the first 3 weeks i didn't feel any different but weeks 4 and 5 were bad. Suffered with really bad insomnia and appetite loss - lost nearly a stone in a fortnight. Week 6 i started sleeping a bit better but it took until week 8 before i started feeling any better and my mood lifted. Negative thoughts don't linger in my head as long as they had been doing recently and I was back out socialising and exercising which are obviously important for your general frame of mind.
I nearly sacked off the pills after 4 weeks (because i'd been used to feeling better after 2 weeks in the past) but the advice on this particular forum helped me stick it out which i'm glad I did.
So I suppose what i'm saying is don't expect a quick fix, even if that's been the case in the past, but persevere and hopefully you'll come good.
Good luck everyone.