I've often done award stays (both regular and FFN) within one week, just need to call for reservations. The shortest reservation notice for me was on 7/31 when I called at 7PM and arrived at 8PM at the Stanhope Park Hyatt because I got stranded at JFK by DL. It was a pretty expensive stay at 24,000 points but still a good deal since otherwise it was a $350 rate.