I'm naively hoping that I'll go into labour during the evening, overnight or while DD1 is at nursery, and that labour/birth will be as quick and easy as last time, so that she can either come downstairs or arrive home to her new baby sister.
I'm preparing for the fact that it's more likely to kick off early morning, late afternoon or over the weekend, and therefore DD1 will instead become my littlest birthing partner.
I'm not too worried. She's sensible and mature for her age and made of stern stuff, so unlikely to be fazed.
I've been gently preparing her appropriately, mentioning things like I have lots of extra blood at the moment and I won't need it once the baby arrives so it can come out and that's not a problem. I've also shown her the very first pictures we took of her - about 2 minutes after she was born while she was still attached to me! She was fascinated.
Our nearest family is at least 2 hours away, so not much chance of anyone getting to us in time - especially if things go the same way as last time. I woke around 4:30am with contractions, called the MW's at about 7am when I was sure it was labour. First MW arrived at 8:30am (awkward shift change timing), second MWs arrived at 9:20am, DD1 arrived at 9:23am. G&A arrived at 9:30am. 
No idea when my waters went. They hadn't gone when I was examined at around 9am, so I assume they went in the birthing pool between then and when DD1 arrived. I don't think she was born in the caul, but I was a bit distracted by the real live baby that had just appeared in the water to really pay much attention! I was the only one in the room at the time, so no-one else could have seen.
We have a few friends that would help out in an emergency, but that's more for if I have to do a hospital transfer or similar. At worst, DH is in charge of DD1 and I'll birth alone. Which is fine, I'm made of stern stuff too. 