I get a lot of questions regarding how much money can be made from music licensing. There are many variables so there really isn't a one size fits all answer. I know several musicians who make very good full time, six figure incomes from music licensing, and I know quite a few more that make substantial part time incomes that they use to supplement their total income.
As record labels continue to flounder and as the internet continues to make it easier to reach new music fans, it has become apparent that musicians are in a new and unique position. Creating a viable and sustainable music career without the assistance of a behemoth record label has never been easier. Not that it´s a piece of cake. But it's doable, and more and more musicians that I know are taking matters into their own hands and creating their own fate. It's really inspiring to watch!
Licensing your music should be a part of your overall career strategy. I can't think of a reason any musician, regardless of what stage you're at, wouldn't want to take advantage of licensing their music in TV and Films. If you are managing yourself and you're also concentrating on developing a performing career, then you´ll need to manage your time accordingly. But I would suggest spending some time, maybe an hour or so a day, pursuing licensing opportunities.
Keep in mind that although like anything else you'll need to continue working on the licensing aspect of your career, it will be easier to maintain over time, as you become more established. Working with a publisher, if that's the route you go, is sort of like working with a manager in the context of the music licensing niche.
So although in the beginning it might take you some time to find someone to represent you, once you do you'll have someone that you'll be working in partnership with who will be helping you get your music into the right hands on an ongoing basis.