They give you a ticket with a number on it and the other half of the ticket will be attached to your passport. At 2pm, they will take you up to the 12th floor and everyone queues up. It takes about 5 minutes if there are no problems with your visa. Most people were gone by 2:15. I was there until 3:45 because there were problems because of a prior refusal. Traffic going back to LAX will add time to your journey as well, even though it's only 10 miles to the airport from the consulate. I had a 6:30pm flight back and had to return a rental car as well. I got there in plenty of time (about 4:45pm).
