I edited the live date on a comic so that it would come out next Saturday, but it didn't delay publishing. It published it right away. Is it possible to delay a comic's date so I can publish comics in advance? How?

I've had the same problem today.  

This might be because you're logged in to your account- When you're logged in you see all the pages you've uploaded as if they're live and published. Try logging out and looking at your comics again.