Aww reading this made me smile, remembering my own parents dropping me off at uni (first child in the family to live away from home was a big deal - even though I was even closer than your son is, haha)!
Don't feel bad he hasn't responded to your text - he's got a lot on his plate right now with the welcome week, & I've learnt this generation doesn't see it as 'rude' to not respond in a timely manner to DMs/ IMs (I know I'm not that much older but my youngest sibling is GenZ, so I feel like can say this based on my observations of receiving many meme/ GIF responses haha).
When the activities aren't happening though, being left alone with your own thoughts can also be a little overwhelming. I did feel homesick at times, even if I didn't show it to family. But it sounds like your son's university is much more involved in helping them to settle in - I wish I had 'moving in' volunteers to help move my stuff, haha!
Agree that you can always make an excuse to go see him in a bit, but my advice would be maybe not on the first weekend there - if he hasn't lived away from home before, then that's his first chance at true 'freedom' (& to see any of his friends that work part-time) before classes start 'seriously' lol! He'll fall into a routine of balancing visits/ socialising & school soon enough, but you have to give him the space to be able to figure that one out first (in a way that works for his schedule).
