Hi, Candy...sorry to hear you're still not feeling better.
The lithium should kick in when you reach the therapeutic blood level, between .7 and 1.0 meq/l (don't ask me what that means). So, it depends on how much you're taking, what form, your weight and metabolism, blah, blah... at any rate, there's no set time or anything like that. When they put me on it in the hospital, they did blood levels every other day, I was in for ten days until they got it right.
As for the anti-suicide thing, that's derived statistically.... bipolar patients who take lithium have a lower suicide rate than other forms of treatment. I'm not sure that an antidepressant effect has been demonstrated for lithium, though some docs will get you stable on lithium and then give you antidepressants. You might want to check at
www.psycheducation.org. There's a lot of info there about this sort of thing.
And if you're feeling that bad, call your doctor! They can't help if they don't know!
Keep smilin"!
DJ