Osman II was pretty young, but recognized the growing problem of the Janissary corps. His intention was to create an ethnic-based national army but he was killed in a Janissary uprising aided by the various officials (most likely an in effort to save their own lives and/or restore order) in 1622 when he was 18. The challenge is to find a way to achieve an *Auspicious Incident 200 years early, either full on from the beginning or more gradually with the eventual replacement of the janissaries by ethnic turkic peoples.
Bonus Points for a successful Constitutional Monarchy before the end of the 19th Century.