You need to ask yourself what your greatest risks are for your business. Especially since you're self-funded and bootstrapped, I would not wait to validate whether people will pay for your product. The beauty of someone paying is that not only does it validate interest, but they are then *invested* in your solution. They now have expectations for what you are going to deliver to them. On the other hand, think about all the free stuff you pick up at conferences, trade shows and walking down the street. How much of it was there ever a chance you'd pay for it? Much of it is unlikely you would. That means you run the risk of having people kick the tires on your product and never be really interested in what you're doing or paying anything. Happy to talk further and help you better approach your customer discovery as I've been doing custdev interviews for 4+ years.