The first Guild Wars 2 beta weekend event will take place from April 27th until April 29th. The announcement came via Twitter.
Good news!First Beta Weekend Event will be from April 27-29. We will let you know once the client is ready for download. ^MK
— Guild Wars 2 (@GuildWars2) April 18, 2012
Registration took place in February with over 1 million people signing up for the chance to be a part of the Guild Wars 2 beta. Those who have pre purchased the title will also have access. Details for when the game client will be available will be announced in the next few days.
The forums will also be closed until closer to launch though Beta forums will be up and running during the Beta phase so people can post their findings.