Went to a college career fair and was told I'd be contacted.
I received a phone call a week later to set up a phone interview. On the scheduled interview date, I received a call 45 minutes late saying they wanted to reschedule. This happened twice over the course of 2 weeks. The third time the phone interview actually went through and I was put on the line with an engineering manager from the Grasshopper project. I was told by HR that the interview would be basic/behavioral, but my interviewer asked me a couple of technical questions that I wasn't prepared for. I got a call 3 weeks later saying I hadn't gotten the job.
Overall, SpaceX is the best at what they do and they know it. As far as the HR department goes, expect the unexpected and don't be surprised if your first interview gets delayed.