It is now nearly three weeks. Two weeks on 10 mg, six days on 18 mg. He weighs about 26 kg so the target dose is 25 mg (because I cannot afford to buy two separate boxes of medication) but you never know if a lower dosage is effective so we have agreed to try him on 18 mg for four weeks and perhaps longer.
A better evening tonight - no meltdowns, no rages, no cross words, happily to bed and long storytime.