Depending on where the airport is, I've generally thought that checking the bag early may increase the pilferage opportunity. (FWIW, the 4 or 5 times my bags were attacked all occurred when I'd checked in at least 90 minutes before departure). While I've also thought that checking in late increases the chance of the bag not making it onto the plane, the 3 instances I've had where the bag didn't make it have all occurred when there was over an hour to get it on the plane.