I was the same as you when expecting my first. And whilst I knew that friends would loan me clothing for the baby, I was sure that she would arrive during the winter break, when everyone was out of town, and there would be a snowstorm. Added to the fact that we did not own a car, I found that buying just a few sleepers to last us the first day did help me to feel less anxious about baby arriving and having absolutely nothing. That peace of mind was very important to my health, and I think that if I had asked a shaila (didn't occur to me, as we did not have a strong minhag, anyway) that I would have been told to go ahead (based on other things our Rav has paskened on for us). We did not have any family in the area, so I think that was a factor in needing to be somewhat prepared.
We did the registry thing at the baby store, so that dh could call them and have everything delivered afterwards, but, although we were able to pick everything out ahead of time, we did not actually buy it until afterwards.
The only thing we really had to buy and have delivered beforehand was the car seat. We bought it through our health-insurance company, which got us a discount, and it sat at home until baby was born, so that we could bring her home from the hospital.
Sure enough, by the time I got home with the baby, friends had delivered the bassinette, the clothing, etc, and we were fine.
This time around, I need to buy a car seat, a new stroller (though that can wait) and more diapers, plus post-partum supplies for myself. The hospital tells you to bring everything, including diapers and pads. I'm doing all my research now, but will probably only buy the diapers (we use cloth, so they need preparing), postpartum supplies and car seat in advance. Again, I don't want to leave it too late, because I have a history of needing bedrest at the end, and because if there is a specific car seat I want, I don't want to find out that it isn't in stock once the baby arrives. Also, the timing of my due date is such that there is high probability that I will need to leave the hospital motzei shabbos or motzei yom tov, and so it won't be possible to buy the carseat between baby's birth and coming home.
Another alternative, thinking of it, is to arrange ahead of time to borrow a car seat from a friend, and have them prepare it, but that's so weird to me, because for years we have been loaning our baby stuff out, rather than borrowing anything! Oh, and I will be collecting up the stuff we have out on loan towards the end of the pregnancy, and washing everything in preparation.
Hope this musing has helped you with your decision-making!