There is no percentage. Before you ship a product for the first time, it should do what is supposed to do. For example a todo list should be able to manage tasks. If it does that you can ship. Is it speedy, may be not, that is not essential.
Identify your core offer (easy to use todo list). Once you cover it you can ship. Everything else (marketing, security etc) can be done afterwards. + In the mean time you will gather feedback.
