They didn't get back to me after a month when they had said it would take 2-3 weeks, and the PI obviously had forgotten. A whoops moment on their part, but embarrassingly unprofessional

I initiated contact with the PI online before sending in my application. The interview was scheduled a little less than a month after I sent the initial email - responses were timely and clear. During the interview itself, I met with the PI, three post-docs, and the lab manager. I was asked typical questions about my own research interests, and my future plans. I researched the different projects going on the lab beforehand, but was not asked much regarding the specifics. Everyone I met with was friendly and seemed very comfortable working while I was around. The interview style was somewhat casual, and I felt very relaxed.