How to stop procrastinating?

I am supposed to have a 20 page workbook filled out by tomorrow at 1:30. I still haven't done a page. This isn't the first time this has happened. I work around 25-30 hours a week from 4-10 Wed thru Sun. It seems like I never have time to do my homework. I always get distracted by something and wait till the last minute to do it. I'm about to start college and don't want to be like this. Any help?