Does it REALLY matter which date to take the MCAT? Jun 17th or July 8th. I want the extra 3 weeks to study, but I don’t want to be late! 
Take the extra 3 weeks. July 8th is still relatively early (despite what the masses on SDN will tell you). I would, however, be working on getting your AMCAS complete, personal statement done, letters of rec uploaded to whatever service you’re using, transcripts sent in to AMCAS, etc, etc, so that you can hit submit on that baby ASAP after getting your score (if you are planning on waiting for your score before submitting). Many people wait to submit transcripts to AMCAS until after they’ve submitted the application, which slows the verification process down. If AMCAS already has your transcripts by the time you submit, your application will immediately go in line for verification.