It's never coming.
A couple of things, first Q2 ends June 30th not May 31st. Q1 Jan - Mar, Q2 is Apr - June, Q3 July - Sept, Q4 Oct December. Where or who said Q2? T-Mobile doesn't give release dates they only show that it is expected to get one and assigns it to either MFR Development, Testing, Available and will just refer you to this site to watch for updates. LG V10: Manufacturer Development
They don't give you dates because all of the development and programing of any update is done by the manufacturer in this case LG, the fact that it is on this site says that LG told TMO it would be providing an update and TMO agreed to go thru the testing process to certify it on their network.