Just taken first 10mg of ritalin, (methylphenidate) and was wondering what to expect? the psychiatrist implied it would be like night and day, does that sound right?

Usually quickly : These drugs work pretty well in most people who take them but there is always a range of responders. You will just have to see. It also depends on how big you are. If you weighed 220 pounds you would not expect to have the same effect on you if you only weighed 110 pounds. So depending how you respond to the dose your doc can suggest a change in dose.