As @Crazy Cat said, this was back in November 2018, so years ago, came thru LAX point of Entry at 7pm on a Sunday night, drove back to Vegas, got up at 8am the next morning, Monday, was in line at the local SSA office when they opened at 9am with paperwork all filled out. Got the number, and was called to window. showed the paperwork, and he immediately said you just arrived last night, there is no way you are in the system, come back in 2 weeks. I had to push a little bit as I knew it is an instant process when you come thru the POE from a few people I know at CBP, and the SS office higher ups. I convinced him to grudgingly get up from his chair and go to the computer on the desk like 10 feet away ( I know, it was a long walk for him). He keys a few things into the computer, and I see him look back with that look like your wasting my time. Next thing you know, the printer fires up next to the computer ( you can see the amazed look in his face, I just smile). he comes back to the desk with a few pages printed out, and finishes the application, and hands up the paper saying you applied for your SS number, and should have it in a week. He stamped the paper with a date and time stamp ( Make sure you keep this paper, as it acts as proof you applied and it is processing). we left and card was in the mailbox a week later. This was 5-6 years ago that the system updated within 14 hours of POE. If you give it 2-3 days, I'm sure you will be fine.