Imagine that moment where you can walk up to your boss and just say, “I quit.” You can focus entirely on your business without answering to anyone. You don’t have to take orders to work on a crappy product you don’t believe in. You’re completely in control of your own destiny. Pretty powerful, right?

Now forget about it. There will never be a clear-cut point where you can just walk away from your day job. Unless you’re already independently wealthy, there’s no obvious moment when you should walk away. You’re not going to know, and nobody else can tell you when that moment is.

Keep your day job. And don’t daydream about quitting. That job is your lifeline. The longer you keep it, the longer your runway is. When you quit, you put your side project on financial life support. And it’s never going to grow as fast as your projections. All those stories you’ve read about a dramatic moment when someone left their job to pursue their dream full-time? Not so dramatic. And they didn’t happen in a moment.

Eventually you will need to decide if your future lies with your day job or with your side project. The key is to wait until your side project can support you financially, yet can’t continue without you. That’s when you quit.

DNSimple had two other full-time employees before Anthony Eden quit his job to focus on it full-time. Format had seven people on the payroll before Tyler Rooney ever got paid. Rachel Andrew and Drew McLellan wish they had continued working a little longer before going full-time on Perch. Phil Knight had four full-time employees before he went full-time on the company that eventually became Nike.

Find a way to keep your day job. It’s going to be a little painful and uncomfortable, but it gives you strength. Without income from the day job, you’ll be forced into a corner and end up making poor decisions you’ll regret later. Quitting the day job is what you do when your product is growing so fast you can’t keep up with it.

Quitting won’t magically make your product successful overnight. It could still take months after quitting before your side project meets your goals. It could take years. At some point, you will need to quit–and you won’t be ready. There’s never a perfect transition time, but my advice is to hang on a little bit longer than you’re comfortable. It’s not fun, but it lets you stay in the driver’s seat just a little bit longer.

You’ll constantly be tempted by the siren call that if only you’d quit your job, you could give your business the attention it needs to take off like a rocket. Don’t listen to it. Keep your day job. Make good decisions. Quit on your terms.