Living apart together?

For those who do it, how does it work in practical terms?

I'm in a new relationship, 3 months in, and I think things are moving a bit too fast. I'm 48 and childfree, he's 57 and has 2 adult children. I was married for 8 years in my 20s and have been mostly single since then (just flings). He was married for 24 years, had another 4-year relationship, and is the domestic kind (enjoys cooking and has passive income, so he doesn't work a lot). I work a lot and earn more than he does.

He's been sleeping 3 or 4 nights a week in my place, and it's working fine for me. The problem is that he's living with his 86yo mother, who soon will need a caretaker. And I have my own aging parents to care for (they're still fine, but...). In short, I don't want to move somewhere else, and he and his mother wouldn't fit in my 2-bedroom apartment (which I love, for its expansive view and silence).

What is the agreement to live together apart? Do you go to each other's home every night? Do you skip days and nights entirely? Do both have a drawer and stuff at each other's home?

What are the advantages and disadvantages? Me, I'd love to skip some nights, just so I can exist in peace.

And how did you have that conversation?