Very relaxed process. I had applied in the winter for a position and didn't hear anything until of March. I received an email directly from my potential supervisor asking for a phone interview. After the phone interview, I waited about two weeks until the position was offered to me. Know the material on your resume. If you make it to the phone interview, then it's most likely only between you and a few other candidates, as they have a lot of options for interns, which means they must have liked something on your resume.