I think which color, size, Wi-F or G made a difference, and how it was ordered and if it was engraved and knowing Apple, a lot of the sorting orders was done by a computer software program. So, now humans are double checking, notices are catching up but we all need to remember that Apple was flooded with orders, far more than expected.
Perhaps they felt more people would wait to upgrade if they already owned an Ipad, perhaps they thought more people would wait until they could check out reviews from real users, see them in stores. No telling, the economy is still soft here in the USA, even the bottom of the line model is over a week's take home pay where I work and I don't think we are poorly paid in our industry.
Mine is engraved and ordered after Midnight central time so that makes it very early on 3/8 or late on 2/7 if it was west coast time in the computer system.
I am betting with invoice of delivery on 3/16 will actually deliver then and as we set them up we will find the websites at Apple very slow, unable to load due to traffic there and people complaining because the world isn't a perfect place. Hey, if we can afford a new Ipad we have a pretty good life if you look around the world and compare your life to some others.