What is the best time to patent our product?

Your product development process should occur alongside evaluations of how your product might be patentable and, in related fashion, whether your product might infringe another venture's preexisting patent rights. What you certainly don't want to do is "finish" product development, start selling, and then explore patent protection.

There is not a "best" time to patent your product. Indeed, whether you may patent it in the first place is not entirely up to you. Your patent-related timeline integrates your product development and public disclosure timelines, in a sense.

It is advisable to consult a patent attorney in private to evaluate your product and help steer its development with patentability goals in mind.