This is supposed to check on app startup right?
Yes. You need to use the DaysBetweenChecks property as well. Also, realize that if no updates are found the AutomaticUpdater doesn't bother the user. (You don't want the AutomaticUpdater to say "Hey user, look at me! You don't need to do anything because you're already up-to-date! Aren't you glad I interrupted you?)
Also when is DaysBetweenChecks fired? is it time from app startup or calendar days.I don't want 500 clients all trying to update at the same time!
It's from the time the user starts your app.