During take-off & landing, make sure he has a drink to help with the pressurisation - we gave our 18 month old girl a bottle & there were no problems with the air pressure.
Her first flight was to Dubai - we were really woriied about it but there were no problems there or back - she did have her own seat though & VS do supply a babyseat which she was quite happy to sit in for (most!) of the journey!
Next trip to Verona next month!
Good luck