Here is the tenative beta timeline presented by Q-3P0:

During August – Internal Alpha Testing – this will be done with SOE and LucasArts employees. We may invite a few handpicked players (likely long time community people who have helped us out on Test Center) later in August. This will be before we are considered feature complete (hence “Alpha”). During September – Beta 1 Testing – our goal will be to quickly fill a galaxy. The first people selected for this will be the Anaheim Fan Fest attendees. After that will we’ll start to take some handpicked and many random samples from the community (giving preference to long time, constructive community members) In October – Beta 2 Testing – we will open up another galaxy or two to do stress testing and polish.

On a side note SOE has taken notice to the fact that many members of the community are unable to complete the JTL beta registration. Their advice is to close down your browswer and try again. More information can be found here