MW, I guess if I were you I'd try to be as prepared as possible for either due date being right. One thing I kind of wonder is if the whole "40 weeks" thing is actually not as accurate as we think (well of course it isn't LOL) because of the whole assuming women ovulate on day 14 thing. It seems like that could skew the average somewhat, since a lot of women ovulate later than that. And of course we know that 40 weeks is not the true average and only a medical convention anyway...so yeah who knows.
As far as prefolds, I did EC so it's a little different, but DS was 6 pounds at birth and I used Indian prefolds in the preemie size for the first little bit. I like them a lot better than Chinese prefolds. I just used them without a cover, with a Snappi. And BabyCakes, they didn't leak in the newborn stage. When DS got older, like maybe over 6 months, if I put just a prefold on him and he peed in it, it would often leak, but as a newborn, you could tell it was wet but there was no waterfall. I do think I used disposables at night for the newborn stage though. As somebody else said, I think the draw of prefolds for a newborn is the cheapness, especially if you are planning to switch to some other system, like pockets. My diaper stash this time is probably too big - I have prefolds in preemie and infant sizes, a few covers in small and medium sizes, then an assortment of random pocket and AIOs and then I think 9 BG OS for when he/she gets a little bigger. I'm also trying out some small fitteds, they are coming in the mail!
I am getting excited to have a baby! I was a little overwhelmed last week, but I went on a huge shopping spree LOL and have started getting things ready. 6 weeks until I'm "full-term!" My MW said she would probably do a homebirth as early as 36 weeks if I was comfortable with it so that's only 5 weeks - coming up fast! I hope I don't go quite that early but I am expecting to go early (DS was 37 weeks 2 days according to "my" due date).