In my first years of longarming I did charity quilts along with quilting my own. I think you'll find yourself busy with your own quilts, ones you keep and those you give away. I would recommend doing charity quilts too, that will build your skills quickly. I quilted for myself for about 7 years before I began quilting for others. When you start quilting for others it's slow for the first year because you don't have your name out there, people don't know about you yet. But as word of mouth gets out there you start to get customers.
I think you'll do well, you'll really enjoy longarming.