What happens next?

How to stay up for three days straight
Extend your sleep slightly.
You'll want to bank a little bit of sleep beforehand, so don't be afraid to go to bed a little earlier or sleep in a bit in the days leading up to your time up.
Avoid caffeine.
You'll be taking in plenty of caffeine as the days go by. If you use too much in the days leading up to your time, you'll build up a tolerance.