I didn't get a custom theme, ever. I just tweaked the default theme to the point where it was no longer just a default theme with our own banner slapped on it.
Content is more important. If you don't have content, then you're not going to succeed in the forum industry.
I personally still use the default theme for esoTalk on my discussion board since I'd rather wait to have everything matching when Flarum gets released than do it twice over just for the appearance to match.