OP, my son was like this. I did buy his sheets and some other things I figured he'd need, but he was so resistant to packing up, discussing it, etc.
So guess when he finally packed? 4:00am the morning of our departure to his school, which was a 6 hour drive and we were planning to leave at 8am.
He's a very confident kid, not anxious, but he clearly was nervous and had anxiety about this big move and step in life. Drove me crazy, but it worked out and he did great in college.
He leaves next week for the start of his 3rd year and while he's a pro at it now, we'll still have the same, "when are you going to pack up?!" discussion several times next week.