The two-day live beta for League of Legends' anticipated Team Builder feature begins this week on live servers. Each region will open Team Builder testing for 48 hours through a "staggered roll-out." This week, Marhch 3-7, starts with RU and EUNE.
"We took into account the size of each region, the available architecture and hardware, and the current player experience (such as current queue times for all levels) to design the staggered launch," Riot explains. The image below is representative of the live beta test schedule.
Team Builder was first revealed in October of last year as a new queue where you can select a specific role, champion and position before joining a team. The feature attempts to then match you with a team in which you can play that role. Riots hope is to great the foundation for great teamwork by having everyone play their preferred role.
Team Builder will exist alongside normal blind and normal draft pick for unranked Summoner's Rift. If it works well, the developer may look into applying some or all of the features into other queues or game modes later on. Unfortunately, because of the way Ranked works in League of Legends — with bans and pick order mechanics — Team Builder will only be a feature for normal games.
Over on the official League of Legends website, Riot has posted a FAQ regarding Team Builder, answering your questions about queue times, Team Builder captains, and AFKing or rejecting a group you've been played into.