With my last September baby I didn't even buy a car seat until I was late in my 37th week
We ended up installing it as we were leaving the birth center with a 5 hour old baby! Luckily it's a LATCH install in a captains chair, Keyfit 30, doesn't get easier...
This September baby will be requiring a total shuffle of seats. The car seat is stored and a friend is borrowing our extra base. I'll probably pull it out after the kids go back to school September 4th and I predict I will start nesting, with my big girl off to third grade, my son off to Kindy, and only the toddler at home. However, I likely won't install it until we're about to have the baby, as we've got to rearrange everyone's location in the van and I like them where they are!
I also was in a car accident at 38 weeks, with my DS, and I had my DD's seat in the car but had not installed the carrier yet. It was a mixed blessing because it was a Snugride 22 I would have liked to replace! I think, though, that that has made me much less likely to put a seat in soon. I would hate to see it wrecked, or knowing my kids, have them put an ice cream cone in it or something!!