Gamescom starts Wednesday, but the pre-show media briefings begin tomorrow. Microsoft, Sony, Electronic Arts, and NCSoft are the big four this year, each hosting their own press events.

Here’s what to expect:

• Microsoft Play Day – Tuesday, August 16 from 12:30 to 3:30pm
  Like last year, Microsoft will host its three hour-long Play Day event. The Xbox manufacturer’s promised “a preview of [its] 2011 show content and news,” meaning you should expect to see Gears of War 3, Halo: Combat Evolved Anniversary, Forza Motorsport 4, and plenty of Kinect-enabled software. If last year’s event is anything to go by, it won’t be your traditional presser, but more of a hands-on event for the press before Gamescom goes public.
• Electronic Arts Press Conference – Tuesday, August 16 from 4pm to 5pm
  EA hasn’t teased much in regards to its media briefing, though we could take a few cracks at their possible reveals. The oft-rumored Syndicate, Mirror’s Edge 2, Crysis 1 for consoles, and Mass Effect 3 multiplayer are all possibilities. EA will broadcast the presser live at its Gamescom website.
• Sony Press Conference – Tuesday, August 16 from 7 to 8pm
  An hour-long press conference is planned for Sony. The PlayStation company is expected to go detail-crazy on its PlayStation Vita portable, with worldwide dates being a possible announcement. It’s possible Dontnod will reveal their Sony-published PlayStation 3 game during the conference, as the company’s already confirmed the game for a Gamescom reveal. Quantic Dream’s new game is also a possibility, recent rumors suggesting its an Infraworld revival. Sony’s outlined four different ways to watch the conference; choose your method here.
• NCSoft Press Conference – Wednesday, August 17 from 9:15 to 10am
  Massively multiplayer online game publisher and developer NCSoft has promised a “world exclusive” announcement for its Gamescom press event. We’re expecting the firm to announce a new game, and possibly announce release dates for its other titles like Guild Wars 2 or Blade & Soul.

As we’re not all tied to Cologne time, here’s a nifty time conversion chart, courtesy of NeoGAF’s Adriano999:

Stay tuned. The festivities begin in less than 24 hours!