I am a manager and have onboarded several people, and it would be extremely weird for someone to come in a day early. I generally expect the first week or two to mostly be learning how things work, and I've already set up how that's going to work, which includes finding the relevant people to help you out. If someone comes in early, that would be inconvenient for me, because now I need to either find something for them to do, or take time away from my schedule to give them a tour or something. I suppose I could take you to HR to get your bank details entered or whatever, but that's about it.

Please don't show up on a day you're not expected to be working unless that's something you've discussed prior to the start date (i.e. Tuesday will definitely work, but if it turns out I can come in on Monday, should I?). If you show up early on your first day, I'll just have you start on the paperwork and whatnot and I'd probably let you leave early to reward you for your punctuality (first days always suck, and you're helping it suck less). That said, more than 30 min early is probably pushing it, since there's a good chance I'm not even in yet.

Yeah, my response was more related to being expected to show up a day early and how much hassle that would legitimately cause in a general sense. In specific situations it obviously works out just fine. If you have a sense that they would be ready and interested in getting a head start, sure... But to say 'start on Tuesday' instead of scheduling for Monday, and then having even a sense of disappointment that they didn't show up on Monday is beyond ridiculous.