If a storm is brewing (aka recession coming into full swing)... I wait it out. I would keep the job, break into the new business idea, build some cash reserves, then jump. But, heck... it's done. Go for it. Warmest regards, Bill.
The one thing I can say about the economy with absolute certainty, at whatever point in the cycle it is... is that there is a recession coming.
There is ALWAYS a recession coming. Go do your thing. Some of the richest and most powerful men in history began with nothing in the depths of the great depression.