I reckon you should jump straight into the theory. An old lady once told me that while yeah, you can do well on your own without knowing any theory, but if you do know theory, then you'll just be even better. What is theory? It's knowledge. The more song-writing knowledge you have, the better off you'll be.

There's informed practice and uninformed practice. You'll get a lot better a lot quicker if you understand everything about what you're doing.