The waitlist works like a leaderboard, meaning your position is based on the number of points you have.
If you are new to the waitlist, you get 3 points when you sign up. If you joined before November 2017, you get 4 points when you downloaded the latest version of the app (available on iOS and Android) and sign in. For each friend you refer who signs up for Curve, you will get 10 points.
Therefore, your position on the waitlist will move up and down. When others refer friends that sign up to Curve they may jump ahead of you. If you want to move forward, refer friends who you think will want the card too. The more friends that you refer the more places you will jump.