A real validation happens when people start using your app. Better yet, paying you for it. You can discard 100% of what your friends and family say - they are

A real validation happens when people start using your app. Better yet, paying you for it. You can discard 100% of what your friends and family say - they are not in the business of crushing your dreams. Release your app, install basic analytics so that you know how many people are using it. Put a price on it to see if people are willing to pay for it. Full time job is not an impediment to working on your app. Yes, it's going to be harder, but I wrote lots of code and shipped a couple of apps while working full time. As to when to quit - it mostly depends on your level of optimism and willingness to take risks. Personally, I would wait until I have a steadily growing number of users for the app.