The old school method was drops roughly the width of your torso/shoulders, but the tastes seem to have moved on to wider these days, I would recommended you leave them as Wider bars=more power, lower your saddle or shorten your cockpit length, ride it for a month, next time you ride a bike with narrower bars you'll wonder where all your power went, 44-cm bars on a 50 is pretty standard these days.

It might be worth your time to have a local shop or a friend fit you on the bike, regardless of what people tell you it's pretty much impossible to fit yourself 100% on a bike, you can get close, but if you really want it dialed it's two man job.