Great! Happy to hear you're looking to apply. The deadline is next friday. You can find the full timeline here: http://www.google-melange.com/gsoc/events/google/gsoc2013 There's a specific time on that page (with all the dates after the application period close, too).
I'd encourage you (and any other students who happen to be reading this) to get your application in early, though. The earlier it's in, the more time the mentors will have to provide feedback (and you give yourself more of a buffer against unexpected issues). Anthony