If you dont hate your job, I would suggest you to stay in your job until you validate your idea. It allows you to keep earning money while you are not actually building anything (validate an idea is not a fulltime job). And also it helps to keep you in the right mental state that your first idea most certainly isnt the right idea.
If you quit your job with an idea in mind and the plan of validating it then executing, it will be much harder to change or even discard this idea ("this idea is why I quit my job afterall!").
Validate your idea (with or without a MVP) before quitting your job. That's my two cents