My thought as well. Mine originally had a March 18 date and said "preparing to ship", now it's still "preparing to ship" but the date has changed to the March 30-April 6 window.
In the past, early first-day orders arrived on launch day, so I expected it to show up on the 18th. "Preparing to ship" usually mean t it was queued up to get on a plane to the US. Disappointed that it's still sitting around somewhere in China.
Plus, all of the Boston-area Apple Stores sold out of the ones available in-store yesterday, so I'll have to just sit tight.
I do have a lovely new keyboard, though, which I'm getting practice typing on. All the years of MacBook keyboards makes me stumble around hunting for the Fn key on this one, which I didn't realize I used so much.