I would definitely arrive earlier on Thursday if you can. Unfortunately you probably won't know the situation until that day on what your cadet will be able to do and it'll probably change even then. First of all, we were all told that for sure our cadets would have their phones back so we'd be able to coordinate. Due to a miscommunication in my son's squad (U/C had them locked up and was unavailable to give them out and no one else had the combination), they didn't on Thursday at all. So we were communicating by email. Before we flew out, we had heard that we "might" be able to see them by the chapel wall, sometime around dinner time, maybe for an hour. Since we were traveling with our two younger sons, we'd arrived late Wednesday night and were spending the day out at Royal Gorge Park (about 1.5 hours from USAFA).
Around lunchtime we got an email from our cadet saying, basically, "Hey, I can see you now if you want!" Needless to say this was extremely frustrating since we hadn't seen him since June and were now too far away! We asked if we left then if we could see him as soon as we got there, but he then had class and D&B practice. We drove back, emailed him again, and he was able to meet up with us for about a half hour before his practice, but literally, we followed him as he rushed from his room to go get his instrument and then make it down to the parade field so we didn't actually get to socialize. We were able to sit and watch his practice (as were most sport/club parents we talked to that afternoon), and it was fun to see, but again, still not time with him.
He was told then that he would be able to hang out with us for the evening so we followed him back to his room where he was NOW told to get ready for a Knowledge Bowl. We were invited to attend; many parents from other squadrons we talked to were not allowed to go to theirs. But still again, this was a fun way to see some of his life, but still not actually get to talk to him. After the K-bowl (around 7:45 by this time), he asked if we could go to A-hall with us and received permission but was told he had to put on service dress. Only to get to A-hall and be one of maybe 3 people total in the dress uniform (and I think the others were on guard duty there!). Funny though because as we walked through the darkness in the dress uniform, I think all his classmates couldn't see his boards (he's 6'4) and assumed he must be an upperclassman so he was greeted by around 20 people on the way! We spent around 1.5 hours with him eating and talking at A-hall, but we were exhausted (late flight into Denver and didn't get to COS until around 1:30am the night before) and he had homework so we left him by 10 or so.
So my point is, if you have the flexibility to be there Thursday, you may get to spend more time with your cadet. Especially if you can't make it out for A Day, this may be important to you to have every minute you can. I wish we'd been nearby because it sounds like we could have had a couple hours with him between lunch and his late afternoon class. But keep in mind that it all may change. Their particular squad may tell them they're restricted to the squad area or can't see parents or they may have more classes (they'll know this in advance) or duties. For the most part though it seemed like if they were free (between classes or after class or in the evening) that they could meet you either by the chapel, down by the field house, or wherever you coordinated (the field house was the closest point out of the secure area from my son's dorm area).
Regarding the rest of the weekend, you definitely want to stay nearby on Friday night. Most squads have a mandatory open house (which was just a briefing - not a tour of the squad area as I'd been expecting) which lasted until around 5pm. Our son had to be back by 6:30 in the morning for D&B - most others I think not until at least after 9 or so. But with Friday night traffic and then getting back onto the base, you don't want to be driving to Denver that evening. I would say though that Friday is essential to be there for. Yes, it's "just" classes, but there's also a parade in the morning, lots of activities (and pictures, etc.) at A-hall, and your cadet will want to show off their classes/teachers/friends to you. I felt really bad for the kids in the classes we went to without anyone to introduce or talk to during the class. Most of the classes that day were low key and there was a lot of down time. And you can go to lunch at Mitch's which you won't have many other opportunities to.
Saturday morning will simply be the squadron tailgate near the stadium and then the game in the afternoon, but it will still be at least late afternoon before you leave. It sounds like such a long visit but there are so many activities that it seemed we really had very little down time with our son. Finally, if you at all can, they won't need to be back until 7pm on Monday and probably will prefer not to be any earlier if possible! So if you can take either a very late flight (not possible going east we found) or fly out the next morning instead, your cadet will appreciate it! If you can't, have them talk to their roomies/friends and see if there's someone they can hang out with that afternoon if you do leave earlier.