While I've experienced procrastination that had nothing to do with not having a good plan, I've also had the kind that does. And it's far worse.
Some procrastination occurs because we know we have time, and other things seem more important or fun.
Lack-of-plan procrastination is worse, though. You delay until you have a plan, but without a plan, you can't know if you have time to finish. That -should- push you into making a plan immediately, but the whole enormity of the situation causes a panic reaction that prevents you from thinking rationally about the plan to start with. In the end, you put it aside until you can deal with it. It doesn't matter what reason (tired, no time, need something/someone, etc) you give, it all ends up the same.
The only way out of that kind (that I've found) is to seek help. Complain to random people about it, ask people with specific knowledge, etc etc. Just find help somewhere. Sometimes you just need a direction to start heading in.