TV Guide acknowledges that some of this is best-guesswork and may not be canonical, but here's their best shot at a Flash Forward time line.
January 2005 - the Oceanic Six leave The Island
Summer 2005 - Sun-Hwa Kwon and Hugo "Hurley" Reyes visit Jin's Grave
October 2005 - Sayid Jirrah kills Ismael Bakir, who he believes is Nadia's killer.
Autumn 2005 - Benjamin Linus visits Charles Widmore's suite in a London hotel. (exact date or chronology unknown)
Autumn 2005 - Sayid kills Mr. Avelinno on the golf course.
Autumn 2005 - Sayid kills Ilsa.
Autumn 2005 - Hurley sees the late Charlie Pace at the convenience store
Autumn 2005 - Jack Shephard visits Hurley at the mental institution
? 2006 - Jack Shephard testifies (and lies under oath) at Kate Austen's trial.
Autumn 2007 - Jack, Kate and Aaron Littleton are living together as a happy family during this period.
late/Winter 2007 - A break-up with Kate, guilt, booze and drugs lead to bearded Jack's suicide attempt.
late/Winter 2007 - Jack reads an obituary and is the only person who shows up to a closed coffin funeral.
late/Winter 2007 - Jack meets Kate and tells her they have to go back to The Island.