How do you make sure that you show up on time to things you're supposed to show up on time for?

I personally set all my clocks anywhere from 10-15 minutes fast and some how convince myself that I have to be at places 10 minutes before I have to be there.

Except for a class I have at 850 in the morning. I have a class at 745 in the morning I have less trouble showing up for, but there's something about this 850 class that I just can't make on time.