Keep an eye on the headaches - sometimes stimulants can affect blood pressure and a head ache can be a symptom. For my son, lack of appetite and difficulty falling asleep are the two main side effects. Sleep tends to resolve itself in a week or two after he gets accustomed to the medication after being off of it for awhile (summer and vacations).

Based on what you report - it seems like the trial is successful. As DeeDee says, you can tell immediately (well, within 30 minutes) if the stimulants are working. Sometimes there is a let down when they wear off (sadness, mood swings), but again, you would see that the first day.