Not quite the speed record some of you have, but I have been having a very fun game as PRU the past couple of days.
Early war with DEN, take HAN and SAX via influence: NGF. Foreign investment really helps keeping your SoI safe.
BAV has become a GP, forged a humiliate CB but, they have Allied with Russia. So be it, attack anyway.
BAV mostly occupied, starting the beat back the Russians when AUS, allied with FRA, TUR, and some minors, attacks me! Luckily most of FRA's forces are off fighting Spain. Focus on finishing off Russia's armies, and get them to peace out for humiliating BAV. Manage some good victories against AUS before Spain falls and FRA brings up more troops. TUR troops start appearing in Austria too.
Around 5 years after attacking BAV, the Austrian alliance is defeated. FRA and AUS are humiliated, FRA gives up A-L, AUS admits my hegemony in Germany. The German Empire is founded in 1854.