usually when starting a new med, there is a trial run while the body adjusts to the sudden influx of medication. You usually then have to bump up to the next level and then wait to see if that runs out or not, until you reach the appropriate dosage.
My oldest never moved beyond the first dosages (worked fine but then brought out anxiety) and he's now on Intuniv (2nd dosage). My youngest we needed to bump his focalin up within 2-3 weeks of starting (and probably need a booster dosage as well)