Charles doesn't live with us, so he doesn't have a room here. The master bedroom is generally viewed as mine because it always has been, but Henry sleeps here and has his stuff here whenever we don't have other guests spending the night. There is another bed in a corner in our basement when Henry has some other stuff and he sleeps there when I have company, but it's not really a space he shares with guests. It's also a much smaller bed so I wouldn't want to sleep in it with anyone; I much prefer the space in my own (Cal King).
But yeah, I guess I didn't explain very well that with one or two exceptions, it's not really about what day we do it- just that if we're having a party or event in the shared home, that it feels difficult to manage things. We do kitchen table poly, which still feels like a bit of a shock to me since I never thought it would be my thing, but I admit it makes life a lot easier sometimes. Henry and Charles get along very well.
If we ever all live together, which isn't even on the table at this point, I would want each of them to have their own room here. Then that would alleviate this particular issue, but raise a great deal of others. For now, I wouldn't be comfortable with that kind of escalation. Living with someone, to me, comes with way more emotional intimacy/expectation than I think it does with most other people. I would very much view that as a relationship escalator step and it's way too soon for that for me anyway.