Good advice.
Even if they have ropes blocking off the park, it's always good to be there 30 minutes early and wait. A few minutes before 9am, the line streatches back to the ticket booths. You don't want to be waiting in that. It's better to get into the empty park, and then you're first to the guard at the bridge leading to Hulk. On extremely busy days, they may open early, but it's not posted anywhere.
Park opens at 9am, so I'm there by at least 08:30am. Often, I arrive at 08:00am and walk slowly thru city walk. There is excitement in the air as I walk to the gates. The time goes fast.