When in 2017 did you take it? I believe the expiration date is 3 years from your test date? Please correct me if I'm wrong on this.
Assuming your score hasn't expired, you can definitely apply to schools with the old score to get verified early, while you wait for the new score to come in (I'd make sure that the old score is high enough that you wouldn't get pre-screened for secondaries at the schools you're applying to). On AMCAS, you can put in a future test date so schools are informed about a future score coming in.
Couple things to note:
1. The schools you apply to will see all of your scores, not just your latest.
2. You won't be considered 'complete' until you submit both primary and secondary apps as well as your new MCAT score. So if you haven't received your score back, they won't review your application even after you submit your secondaries.