The first time around, I had barely begun packing my bag the day before I went into labor about 3 weeks early. I think I felt more concerned about going post-dates than early, yet also a bit superstitious, like if I packed my bag too early then it would happen earlier. I ended up with no slippers and one baby outfit at the hospital, lol, and my feet swelled up to the point that I had to wear the shoes I wore into the hospital as mules. In retrospect most of the things I did the last day before I went into labor were nesting behaviors, but I didn't quite nest enough to get the bag completely packed and mainly missed my slippers. The infant seat bases were installed well in advance in both of our cars because the cars (Saturn S-series models) and Evenflo infant seat were kind of challenging for carseat installation.
With baby number 2, I installed infant seat bases and packed bags about 6 to 8 weeks in advance, and kept a bag in the back of my van from that point forward. I knew we likely would need to move quickly when the time came and wanted to be as ready as possible, plus I was extra concerned about going into labor early and quickly. I actually would have loved to have had planned home births but our insurance coverage and a reluctant DH had other policies.
I really hate hospitals and was not eager to get there too soon nor stay longer than absolutely necessary, but I also didn't want to give birth by the side of the road. I intentionally didn't bother to pack slippers when packing for baby number 2, preferring to wear some Minnetonka mocassins that were extra roomy and still fit no matter how much my feet swelled.
All I can say in retrospect is thank goodness it wasn't rush hour or else it would have been a minivan birth despite the advance preparation, lol.
Hope everything goes smoothly for all of the expectant mommies.