As you might have guessed, Tuesdays got the most guesses (since that's usually when Blizzard updates the realms), and Tuesday, March 18th got the most guesses overall. Adam's predicted date of March 25th got the next most guesses, and strangely enough more people thought Blizzard would wait until the 8th of April rather than releasing it on April Fool's Day. Also, there are a lot of days missing between 4/1 and 4/8, so while we don't know exactly which date those 11 people in between guessed, odds are there are some days missing in that stretch that didn't get guessed, so if Blizzard decides to release the patch on a non-Tuesday (remember that the PTR went up on Friday night), we might have an interesting outcome.
My official guess was before Noblegarden (which starts on 3/23), so looks like I line right up with what most readers thought: we're all expecting the patch on 3/18. Now it's just time to wait and see when Blizzard decides the patch is ready. Thanks again to Ian for putting this together -- fascinating stuff.