Which day would be better?

Me and several of my friends are planning on going to CP the weekend after school ends (Saturday is June 9th and Sunday is the 10th). We would have liked to go on a weekday, but the weekend was when everyone was available. If we decide to go on Saturday, we were planning on getting Fast Lane since I know it will will packed. However, I just asked them about possibly going on Sunday instead. I think it would be less crowded. If we do want to try Sunday, do you think we'll still need to get fast lane if we want any waits under a half hour? And would Sunday for that weekend be busier than normal sundays or would it be pretty empty? Since we're just high school kids we would be willing to pay extra for fast lane but don't want to spend that much extra money if possible. Plus this is my first time visiting the park during this time of the year so I'm not really sure what to expect. I'd greatly appreciate any help or advice since we need to have our plans finalized in the next couple days. Thanks!