I'm recently diagnosed with ADD and am trying out different stimulants to see which one works for me. How long does it usually take for you to know if a stimulant is working for you or not? Is there an initial time period where you will see bad side effects, that will later go away with steady use of a drug? If so, how long does that initial time period usually last for with stimulants? For example:
I have been taking focalin for two days and don't like how it makes me feel when I'm on it and the coming down is more of a crashing down which lasts over 4 hours...uggghh...should i still keeping taking this drug?

2 days at a starting dose is not really long enough. Usually a doctor doesn't give you a large enough dose at first to really tell if and how much the drug will help you at the thereaputic dose. Often people will feel a slight improvement from the get-go, even at the lower dose, but feel they need more or that the improvement they saw on the first or second day is gone by the third, etc. This is a sign that the doseage isn't large enough yet.
In practical terms, you should give the medication at least a month before writing it off - unless you have intollerable side effects or the drug isn't working at all, in which case I'd talk to my doctor about a change earlier than that.
Good luck,
Greg

Often people will feel a slight improvement from the get-go, even at the lower dose, but feel they need more or that the improvement they saw on the first or second day is gone by the third, etc. This is a sign that the doseage isn't large enough yet.
So if I don't see improvement by the get go should i not continue the drug?
Also, if the drug still makes me feel bad after three or four days should I keep trying to get used to it or try another drug.

I had tried 3 different meds in less then 1 month. If its making you feel like crap then I would stop taking it and try a new one.

How long should you keep trying? It depends on how bad the drug makes you feel, I guess. If it's making you feel bad, then there must be some kind of effect - the drug is working, just not in the way you'd like. The side effects usually get better with time, so if you can endure them at first, it's worth a try??? You may see an improvement at a higher dose, or perhaps not, but without trying, you will not know.
Patience isn't exactly an ADHD trait, but you have to realize that it will take time to find the right medication at the right dosage - don't expect to see a solution in a month or two. It's reasonable to expect to see some improvement within that time frame, but you won't have worked out all the bugs by then, unless you are lucky. The trouble with switching meds very quickly - like 3 meds in a month - is that there won't have been very much time to get used to them. If the side effects are so intolerable that you have to change, then there isn't a lot you can do really, but you quickly run out of possible medications to try. I know from previous posts that you have asked for Adderall and that your doctor has initially refused to prescribe it - anti-adderall as you put it - so your options are further limited by that fact. I wouldn't expect that he'll change his opinion any time soon, especially given the flood of illicit Adderall use on University campuses - check out this article from the Yale Daily News as an example:
http://www.yaledailynews.com/article.asp?AID=27960
Given your situation, it's going to be difficult to get a scrip for Adderall - Young male college student; newly diagnosed as ADHD; has tried Adderall before w.o. scrip; requesting Adderall specifically; tried Strattera, Concerta and Focalin but quit each due to side effects after less than a week or two; disorder with a clinical diagnosis (no test exists to confirm the disorder); disorder that is frequently faked by students in order to get medication; and the most popular medication for said disorder is also the most popular prescription drug used illicitly on campus.
A cynical physician is simply not going to prescribe Adderall in such a situation. The amount of time that you have allotted for the previously prescribed medication to take effect is quite short, and could be construed - by a cynical GP - as "half-hearted", despite the severity of side effects.
I don't know what kind of relationship you have with your doctor - has he been your doctor for long? - but without a trusting relationship, I'd say there is zero chance of getting Adderall, so it'd be in your best interests to give your current medication a full trial - as long as you can live with the side effects. My guess is that your doctor will try you on Wellbutrin next - not Adderall.

my problem is opposite though... I asked for Strattera b/c it is a non-stimulent and my doc refused and insisted on putting me on Cylert... which so far, I am NOT loving! But I am trying to be patient and give it a chance to work.