I update this every year. These are the first mentions of people getting the email, but some do receive them later:
2020: Tuesday, March 31 (right near midnight 30/31st)
2019: Tuesday, April 9
2018: Tuesday, April 3
2017: Friday, March 17
2016: Tuesday, March 29
2015: Tuesday, March 31
2014: Tuesday, April 1
2013: Friday, March 29
2012: Friday, March 20
2011: Tuesday, April 5
2010: Tuesday, April 6
2009: Friday, April 10 & Tuesday, May 19 (released in 2 batches)
2008: Tuesday, April 1
2007: Friday, March 23
2006: Thursday, March 30
2005: Saturday, April 9
2004: Thursday, March 18
2003: Friday, April 4
2002: Friday, March 15
2001: Tuesday, March 20
Pretty consistent Tuesday or Friday for the past 15 years. Usually near end of March / beginning of April.
Some kind, neurotic soul from last year made this nifty spreadsheet (thank you, person in old thread!), if anyone wants to obsess more. FYI, the first to post about last year was ~11:15 EST.
Edit: Also check out that thread for detailed analyses regarding average time between maintenance starting and results being released.
