I’d get them to give him a 504 plan rather than the IEP An IEP is for Pre3-12, so technically ends with hs graduation (some colleges will allow the accommodations but they don’t have to). A 504 is more of a life skills/accommodations plan, and not just for education.
You might have an uncomfortable few months, but he really needs to learn to advocate for himself. I remember teaching my kids to fly alone when they were 13 and 14, and we’d be at an airport and they had no idea what to do next and I kept repeating “ASK”. I said I wouldn’t be with them so they needed to ASK someone if there was a gate change or delay or they couldn’t find a bathroom or the next place they were supposed to be. They were both shy so it was hard, but they had to learn it if they wanted to go to visit their friends or grandmother.
Have your son practice at home. Have him buy his dinner and pay you the bill at the end. Have him plan the next weekend get together with your friends. Maybe he and the friend could sit at their own table at a restaurant and order and pay (with you nearby).
If you don’t start, he’ll be overwhelmed with all the changes at college. My friend’s daughter who is 2E was very capable of the academics but when she went away to college, it was all just too much - her medications, the social things, regulating her sleep, the food… she had to do it all and just couldn’t. She finished the first year, took a year off, and then went to a school in town. Her academics returned to a high level because she no longer had the pressure of the social, the food, the medications. If she needed help, her parents could help. Honestly, the social piece just went away and she was fine with that. She had a few friends from her childhood and she preferred them to making new college friends.