From the reading I have done, it appears that you get one shot at the NetJets cadet programme. Considering the observation written here by current cadets and even a NetJets pilot, I think it would be both arrogant and foolish for a 19 year old to apply and waste their one shot on an impetuous application. Why not prove your maturity by taking the good advice offered here and getting some life experience or even a degree if you really want to improve your odds of success?