quit your day job while building your awesome concept before funding?

I was thinking it all right to work on my great concept during my free hours and weekend left from my day job.
however, lately, I feel I cannot use this free time effectively due to job stress and I am at the "go!" part of my concept; marketing plan is unfolding well, good time to connect to partners, seek an early investor and simply network. for these I presume I need to work in peace and do some sound thinking as I could until a few weeks ago.

I am confident of my concept to receive funding, whether from an investor or a startup competition (due to its nature, bootstrapping would apply to only a brief proof-of-concept). but just quitting day job, without no finances as yet in the horizon..while it is also attracting to think that I could progress incomparably faster with dedicating all my time to the launch.

I look forward to your opinions on this case. what would you recommend?

thank you so much for your time,
best greets!

This probably isn't the answer you're looking for, but what makes you think that being unemployed, with no income, working on your concept, will be less stressful than your current situation?

It's a fairly well understood fact that founders/entrepreneurs cycle through a massive range of emotions on a near constant basis. It's entirely feasible to be the happiest person on earth in the morning, suicidal by lunch and back to "meh" by dinner.

Stress, is an internal reaction to external influences. If I were in your shoes, I would start figuring out how to deal with stress before jumping from the frying pan into the fire.

Do you have an estimate on how much time do you need to get the proof of concept working?

Sometimes it is useful to invest some half-baked holidays. Why don't you take a week of vacations to finish your POC?

Ask yourself what could you accomplish in 1 week. That would help you prioritize things to be done and get a real estimate on your launch without jeopardizing your job.

If you don't have a qualified customer discovery and customer validation model with actual early adoption customers ready to buy your product then this is a big mistake. Even if you have those in place there is still a lot of work to do to get to a level of funding and or income. I suggest you read the book "four steps to the epiphany" by Steven blank. I believe that every start-up will benefit from reading this book and see what it really takes to successfully launch and run a start-up.