Because it's often hard to add people to ongoing games, there may be a game started around 12:30; then another "side" game started for others who show up later.
In any case, show up, play a game, have some fun.
This will be my 7th Game Day Event. I've had one a month from the start of the year. I plan on having two in Spanish Fork, where I live, and the 3rd event will be roaming. Giving us a chance to try different game stores.