How long can you delay an Elite tournament?

Today's launch was delayed an hour and 40 minutes to allow the heavy rain and storms to pass. At what point would they have needed to cancel the day?
 
First and foremost, safety is the issue.  If it looked like the lightning was going to continue throughout the day, they'd cancel. How long could they delay the decision? The rule goes like this: the first flight of anglers must all launch with at least half the day remaining. Today that means the first flight would have needed to be out by 10:40. Fortunately, BASS officials were able to make the call ahead of that, getting the launch started at 8:00.