I'd definitely recommend offering some sort of incentive for users to share your app with friends. This will not only help you drive adoption, but also help increase usage if the friends you're going out to the bar with are the ones you just told about the app. (Hopefully it'll be top of mind for at least one of them when they do head to the bar.)

Which leads me to another suggestion - try driving up usage by letting the user input a time to receive a text or push notification that reminds them to use the app when they go out. (e.g. "Want us to remind you about this app next time you go out? Put in the time & date here and we'll hit you up.") Once you have better usage, you can start to look for patterns in days/times that people are using the app and send them push notifications at those times.