I think there is not one clear cut answer to this.
In my personal experience, you'll need a few years of experience to be able to work totally independent and do work as a freelancer. Freelancers usually have a field of experience they know well.
That having said, there are easier coding jobs you can do pretty quickly, like coding static pages (websites that just present text and images, but have not a lot of functionality), with or without platforms like Wordpress.
It also depends how much of an autodidact you are. Most people need some kind of framework to learn stuff, but if you learn well by yourself online, you could teach yourself more complicated programming while starting with making static pages to earn a living.
All in all, I'd count on a minimum of two years of work experience before you are free to go.