MPR's Tom Scheck tweets that the president's speech on Saturday will be delivered at 12:30 p.m. from the Target Center.
White House: Obama's Saturday speech is at 12:30 PM at Target Center. First come first served.
Brauer has the White House press release which says doors open at 9:30 a.m. (so you should have left to claim your space in line, oh about five minutes ago):
This event is free and open to the public. Space is available on a first come, first serve basis. No ticket is required.
All attendees will go through airport-like security and should bring as few personal items as possible. No bags, no sharp objects, no umbrellas, no liquids, no strollers, and no signs will be allowed into the venue. Cameras are permitted.