One of my biggest regrets in my D going off to college was assuming her experience would be just like mine. It wasn’t. I also wish I had talked with her about how much she wanted to communicate. I just assumed once or twice a week. She needed more. And still she became independent. Transitions are hard for her ( but that doesn’t stop her). It helps here if I’m available as an outlet to her concerns during a transition. I never say (anymore) it’s no big deal. I just understand she needs a close connection when in transition. Then once she settles in she’s fine.
Most people talk about how they drop their kid off and a few hours later they leave. Nope. Not mine. We were there for a few days. Don’t think your kid has to behave a certain way. Just be there for him. And let him know he’s not an adult yet. You’ll still be helping him with decisions. You’ll still be parenting him. Because you will. Until he decides you won’t.