Charge for your product from the moment you have a core function working.
Many founders are scared to charge beta users during the early stages of their Saas product development. Perhaps you have only a few features available now, or maybe your product still crashes occasionally, and you are worried about billing beta testers.
Whatever the case, charging your beta testers early is a great way to find your product-market fit and generate some early revenue. In fact, offering your SaaS for free during the MVP stage can mislead you in choosing the right growth strategy.