THREE things you should know about Oktoberfest: First, the 16-day Munich celebration actually kicks off in September — today, to be exact. Second, those in the know call it “Weis’n,” a reference to the meadow where it’s held. And third, “It’s one of the biggest parties in the world,” says renowned Austrian-born chef Kurt Gutenbrunner.

To celebrate, Gutenbrunner is throwing a big party of his own at Blaue Gans, his Austro-German bistro in TriBeCa (139 Duane St.; 212-571-8880).

After riding up Fifth Avenue on the Schaller & Weber float in today’s Steuben Parade, Guten-

brunner will head downtown for the beer-soaked festivities — as will 50 members of the Austrian marching band TMK Nussdorf, who will perform outside his restaurant starting about 4:30 p.m.

Besides the all-important Oktoberfest beer from Munich breweries such as Hofbrauhaus and Ayinger, there will be a Schaller & Weber sausage cart, giant pretzels known as Wies’n Brez’n made with the help of Amy’s Bread ($10), and menu specials like a wurst platter ($18) and sauerbraten ($26).

And let’s not forget traditional music from the Schwarzenegger Connection — “Arnie’s cousins,” explains Gutenbrunner — from 7 p.m. to midnight.

But despite the guys in lederhosen don’t come expecting a kitschfest. “It’s young, fresh and fun,” says Gutenbrunner.

Meanwhile, those who can’t elbow their way to the zinc bar today need not miss out on the party: Food and drink specials will be on tap through the first Sunday of October, the traditional end of the German celebration.