15th February 2017 Microsoft cancels its monthly patching for that month
9th March 2017 Wikileaks press release regarding Vault7, "the largest-ever publication of confidential documents on the agency" according to Wikileaks.
14th March 2017 Microsoft publish security update MS17-010 for SMB Server
14th April 2017 (according to https://www.wired.co.uk/article/nsa-hacking-tools-stolen-hackers) Equation Group (see https://en.wikipedia.org/wiki/Equation_Group) releases some exploits, EternalBlue among them. EternalBlue took advantage of the vulnerability that Microsoft patch MS17-010 fiexed.
14th April 2017 Microsoft publish their triage analysis on the exploits
15th April 2017 Security companies analyse exploits. One example of the anaylisis of EternalBlue is the following:
15th April 2017 Some news sites start to wonder how come that the patch existed before the release e.g. https://arstechnica.com/security/2017/04/purported-shadow-brokers-0days-were-in-fact-killed-by-mysterious-patch/
12th May 2017 WannaCry appears in the wild
Some sources mention that the infection vector was a phishing email
However, no analysis yet of that mentioned phishing email, its attachment and its modus operandi in general.
Update 1: Response and proposals from Microsoft