Microsoft's annual Build conference is approaching, and while the company is yet to formally announce the dates for Build 2019, it appears they have been leaked through a hackathon that Microsoft is hosting.
In the terms and conditions for the hackathon (here via Petri), one of the prizes is discussed, a free pass to Build 2019, but within the terms it states the dates and location for the event. The dates and location are the same as Build 2018, with the conference taking place in Seattle between May 7-9.
No official announcement for the Build 2019 dates has been given yet, so take the above dates with a hint of salt, however, it's a fairly strong indication that those are the dates to expect the conference to take place this year.
It's not known what Microsoft will discuss and announce at Build 2019, but we could be hearing more about the next-gen HoloLens.