Tubes normally run every 5 minutes on the Metropolitain line, journey is 22mins give or take.
The longest bit is from leaving your seat to actually getting on the tube, 5 minutes just to get outside the stadium, then a few minutes walk around depending on where you are seated so by the time you've got onto the tube this could easily be 25-30 minutes plus add another 10 minutes at the other end from getting off the tube to getting onto the platform. The platform you'll be departing from is the 'new' platform 0 (zero), essentially where the old cab driver's lane was and is located at the Easternmost side of the station.
So I would give yourself a good hour so you're not panicking/rushing
HTH