First and foremost, do not quit your day job, even if you get one or two clients to begin with. The freelancing world is unforgiving. I am a freelancer looking to get back into full-time work with a seasonal business on the side.
I saw a need in my region, where these small mediocre businesses have websites from the 90s. I thought, great, a market. There is a reason these businesses have websites from the 90s. They don't care...and mobile responsive, please they are unmoved by the fact that 89% of people look things up on their phone. I mean they don't even bother claiming their Yelp accounts and haven't noticed that people have left horrible reviews about them and again...don't care.
I worked full-time for a popular VPS provider and even their customers were all internationally based. Businesses around here, have never even heard of them and they started here.
I share that to say, as a freelancer, you will have to find clients on a global scale and just by doing that, you are embarking on a journey of global competition. You are competing with US programmers, European programmers and so on.
But please do not be dissuaded by my response. I realize I live in an area that is still holding on to their legacy Perl applications with both hands and both feet. So perhaps in your area you may have better luck. I do believe local is the key. If you can be the local web dev guy and build a name for yourself with SMEs in your community, you will be golden, but if its anything like the part of the US where I live, despite the fact that these SMEs need, I mean desperately need your services, there is a reason why they haven't already bother with someone like you...they don't care. They don't care if their site still says copyright 2012. Which makes you wonder who is paying the hosting provider? They must be on autopay from 2009 and just forgot about it.
So yeah, hold on to your day job until you start bringing in an income that is at least 50% of what you currently make, but you need an actual plan on how you will scale.
Right now with my seasonal business, I already have a plan on how to scale it and grow it, a real plan. I did follow successful developers who successfully became freelancers and it did not turn out as well for me as for them. Either that or they misrepresented themselves. Like getting tons of work on Upwork. You have to submit over 60 proposals a week and you might get one bite. These are actual numbers, I submitted 60 proposals in one week and got one client. I of course had pay for the upgraded account to be able to continue to submit proposals.