In a nutshell: don’t.

Bad situations to wait until the last minute:

• Catching a transcontinental flight
• Asking your secret crush to the prom
• Applying for a summer internship
• Setting customer expectations
• Studying for the SATs
• Saving for retirement
• Giving up smoking
• Asking for a raise
• Teaching ethical behavior to your kids
• Winning a primary
• Asking for directions
• Sharing an idea

And, for balance, two times when it pays:

• Bidding in an eBay auction
• Giving up hope