The date has not yet been announced, but February 20th would be very much possible (just like in 2013).
I usually check Google Finance for these dates. In the right hand side of the page their is an Events calendar. Right now it says Feb 17th (estimated) implying as Benz said that they official date has not been set.
You can also keep an eye on this page: http://ir.teslamotors.com/events.cfm which also has recordings and presentations from previous calls. On that same page there is a section called "shareholder tools" where you can sign up for email alerts if you prefer that.
Like @evanstumpges said, Google Finance is usually a pretty good bet too.
Was it Q4 2012's earnings that they postponed last year or Q1 2013?
Wed, Feb 19. Q&A conference call starts at 2:30pm PT.
Upcoming Events does not show it yet.