Mandbaby
I have had precipitous birth. I was all prepared for a very fast birth, and no way was I leaving the house. I gave everyone the heads up - mws, marked it on notes all over, said I need someone ASAP when I call, wrote out numbers for mws and stuck them by each phone so anyone could ring, kept my mobile in my pocket all the time, prepared a grab bag of birth essentials which I kept next to me all the time in case I suddenly nape ban to give birth without notice.
Most importantly I got DP to exorcise his demons and was frank about the possibility of my giving birth either on my own (I read emergency childbirth, you can get it on amazon) with just him there, with the kids there.
I prepared my older child, who knew exactly what would happen at a baby's birth - being born by Sheila kit zinger, hello baby, good books, but also watched real births online, answered every question in advance. Also knew how to ring MW, how to explain what was happening, how to open door for emergency services, what might happen if the baby comes suddenly.
In the end it was not as fast, so I had notice, and the labour was a leisurely 1 hour 40 minutes. My dc chose to stay and be involved, having learned so much, and was not in the least terrified.
If a baby is coming fast it is usually a good thing, and all you need to do is go with it (and don't worry about cords, we did nothing with our for over a hour after birth, plenty of time for that later)