When is Windows Phone 8.1 going to come out??

I am just so confused about the release of windows phone 8.1 because first it was CES 2014 then rumours came in about microsoft holding a seperate event after CES and then came in a report by The Verge that it's going to be announced at the build 2014 (April) . If microsoft actually announces windows phone 8.1 in april that's going to be pretty bad IMO.