I'm sure you already know this, but keep in mind no two people's experiences are exactly the same. I'll tell you my experience with antidepressants.

I've tried two SSRI's. One worked better than the other, but they both started out with a noticeable difference on day one. I felt better, with no side effects.

After a few days, I kind of felt like they stopped working, which discouraged me. But after four weeks, I started feeling better again. Again, I can't tell you for sure what it means for you, but I did feel noticeably different for the first few days.

For both types, I started noticing side effects after about a week or two. Neither got really bad, and my second type (which I'm on currently), is pretty manageable. For me, both SSRI's caused some excessive sweating, increased hunger, sleepiness, and jaw clenching. Again, they aren't bad, but these are commonly reported side effects.

(edit: I also should add that I don't feel like my meds have "given me my life back", as some reviewers say on various drug sites. They get me through my day, though, thankfully.)

That's just my experience. I hope yours works for you!