The alpha for Epic's Fortnite is up and running as of today, with the studio running the test period from December 2 to December 19, which, rather tidily, is a fortnight.
The alpha is to test that "all of the basic stuff, from the launcher to all the game systems, is working", although unsurprisingly they warn that some elements are "still rough around the edges".
Invites for the event are being sent out now, so if you've signed up check your email, or you can register your interest here if you've not already done so.