Actually, doing magic for 6 months do make you a beginner, no matter how good you do in sleights and tricks. What makes you a not a beginner magician is experience.
Anyways, it also doesn't matter if you have been doing magic for 20 years, cardistry is different and it is a real and long difficult path.
You can start out with anything you want, but most people(including me) recommends you to get XB first. It is great to start out with the basics and it helps you learn other and more advanced flourishes easier later on.
For me, I've been doing this for about 2-3 months, and I started with DnD's dvds. I can say it is really difficult and I can barely do like 5 of their flourishes and I mean barely.
So good luck!