This March date is strange. The book will be finished this week. I think you’ll see it get bumped back to January in a few days. [Emphasis added.]
The artist has previously stated that he sends the pages to the colorist in batches (of three, IIRC) as he finishes them, so they’ve already started coloring the book.
Meanwhile, Flash Secret Files has been solicited…with that same March 24 release date. Could someone at DC have mistakenly updated the website with the date for the Secret Files book?
Van Sciver also remarked on the delays, saying that it’s been taking him two months to draw each book, plus he had some health problems around the time that issue #3 came out.
(Thanks to Wayne Lippa and @MrEPCOT for letting me know about EVS’ posts!)