TSA warns flyers without a REAL ID may face travel delays at South Carolina airports starting May 7, when the rule is enforced across airports across the US.

“If they do not have any acceptable ID, we strongly suggest they arrive to the airport 3 hours prior to their departure time,” Velez told Gizmodo. Even if you arrive early, however, there’s no guarantee you’ll be allowed to board your flight. So it’s much easier if you just have a Real ID that you can hand over to security.

Travelers across the United States will face new identification requirements at airports on Wednesday as the Transportation Security Administration begins enforcing the REAL ID mandate.