Looks like they are doing another weekend pass this weekend. Note that if you have taken part in any other trials (7 day or previous weekend trials) you won't be able to take part in this trial.
Originally Posted by SWTOR
will be another Weekend Pass Free Trial, giving people interested in Star Wars™: The Old Republic™ the chance to take the first steps in their personal Star Wars™ saga for free*! This Weekend Pass Free Trial will begin on Thursday, May 17th at 12:01AM CDT / 5:01AM GMT, and end on Monday, May 21st at 2:00AM CDT / 7:00AM GMT.
(soure)