How to Make Little to No Money With a Side Project

How long should you make little to no money with a side project before you know it's time to move on? There's an intent there, which is I have a side project, the purpose of which is to make some money. If this is really your explicit intent, 6 months, six months, and if you don't see a really promising trend line, ditch it, start the next thing. Do it love and the money will follow.