Wow - what a momentous time! It's bittersweet, for sure.
A lot depends on the kid, but I'll share that our son didn't want help unpacking or setting up his room. It was hard to take a step back from that. I think it helps to trust that he knows how to navigate stuff like where to take trash/recycling and can find the ATM (although my son's roommate couldn't - overprotective parents!). There's probably an RA to help with some basics, and hopefully there are some orientation helpers for various things. My son's school, for example, had upperclass kids there to help haul luggage/boxes - probably you've been notified if this is true, and how to label things with the room number so stuff doesn't get too mixed up. If you get a quiet moment with the RA, you might ask what the 3 best things are to send in a care package. Then send something in a couple of weeks.
Once you get there and unload, you might consider a trip to the local Target or supermarket for stuff there wasn't room for in the car (laundry detergent, for example) and non-perishable snacks. Otherwise, the college bookstore will have all they need - if higher priced. And there's always the online purchasing option.
We parents were asked to attend an orientation/welcome event while the students went off with the upperclass leaders. They gave us a firm lecture - don't call all the time, don't call us. You're done. Other than the bills, your kid is on his own. Don't call the health service to see if he can get a flu shot, don't call the professor to say he doesn't understand the lectures or needs an extension on his paper, and so on. We were more or less prepared for this, but a lot of parents weren't - and obviously, the university wouldn't have addressed it if this were not an annual problem with many parents.
Without knowing your kid, it's hard to predict, but I would say not to be surprised if he's anxious to have you go or is a bit standoffish. It's not personal - it's a coping skill to leave the nest. Try not to leave too many love notes in his stuff - he may find it embarrassing in front of a roommate he's trying to get to know. Maybe 1, if you can't help it! Otherwise, you might mail a card or note to him to arrive in his campus mailbox in a day or so.
Say less than you think you should - just encourage him that he's ready and that there are supports all around him. If there's a problem, you'll get a call. Otherwise, try to rest on your laurels a bit that, as the university told us, you've done your job and he will be fine. When he comes back at fall break or Thanksgiving, he will be far more loving and willing to let you know how appreciative he was of all you did for him. It's a process of learning to miss and appreciating you - so let him go through it at his own pace. Mainly, start him off with a big vote of confidence.
And don't get on the highway right away - take a slow drive through the campus and find a place for a good cry! Good luck - hope all goes well.