Good idea--build the revenue while you're still working, so that the strain isn't directly placed upon the new business.
There's a book and a group on Facebook specifically for people like yourself. It's called How To Quit Working. The book is by Jeff Steinmann, and you can get it on Amazon. The Facebook group is called "How To Quit Working Circle".
I'll leave you to search for those things if you like, because I don't want to be told it's promotional to link to them. This is a person I've learned from, and I believe his book is one of the top three business books I've read in the past 10 years.