I'm not sure, I was thinking the same thing on New years Eve.... I decided not to get it because the Nexon is an American corporation. If I were you I would just wait. Nothing good to buy any ways.
If you are going to buy it anyways this is how you redeem.
1. Log in
2. Go to purchase NX
4. Enter UGC Pin and email
5. Click redeem
If you get a 20$ card, there is no option, so you redeem 10$ twice.