Ok, I've missed out a few pages in between as my computer is refusing to allow me to read the whole thread in one and taking ages to load each page - BUT.
YANBU. I'm glad your SIL changed it so that it was at least even to both sets of parents. I'm not so impressed that this appears to exclude PILs again by setting the Day They Can Come as being one they can't manage.
I'm even less impressed by the "this is the day I'm going to clean" concept - of course, it's her first baby, she doesn't have a CLUE - but she's not likely to be cleaning!
My situation was very different from many - my own mother had died while I was pg, MIL was still over from Australia (for our wedding) and I invited her to come back for DS1's birth. Not to be present at the actual delivery, you understand - but to be around for when I came home. Because I wouldn't have my own mum (not that I expect she would have been much help, she wasn't that sort, but never mind that!)
So MIL was staying in our house - she stayed overall for 8w, 2w prior to DS1 being born and 6w after. DS1 was born at 2am - DH tried to phone her at our house, but she was asleep (obviously!
and being a bit deaf, didn't hear the phone). I phoned my sister and my Dad - they'd both told me to do so - and my sister went to fetch my MIL and bring her to the hospital to see DS1 when he was ~2h old. I didn't see anything odd about this at all, I thought it was lovely that they wanted to meet him so soon. Dad came later in the day, at a more sociable hour, and that was fine too.
I'm not hugely close to MIL - we've very different outlooks on life - but she can't do enough for us (too much, at times!) and always means well. And if she ever oversteps the mark, we can discuss it (or DH can, sometimes, except he has all the sensitivity of a flying sledgehammer) and things change. But still I felt she should be around when DS1 was brand new - babies are so special when they're brand new! [soppy]
I hope your SIL doesn't have a hormonal weepy fit after a few days when no one has made any attempt to see her PFB, but I suspect she will! I'd think about giving her a call the day they get home from the hospital to see if you can take them anything, or do anything for them (and your PILs to do the same) because I think she underestimates how much she might appreciate it. :)