I would straight up ask him how he feels about dating women who have children. In online dating, this is a question that everyone answers when filling out their profile. This is important, imo, for you to know up front, as it could be a dealbreaker if he doesn't like kids (unless you are only looking to date casually and always get a sitter). Better to screen them out early on so you don't waste your already limited free time.
You don't need to volunteer any specific information about your child, e.g. age/sex at this point. I would ensure all my safety checks and screens have been done before sharing anything about your child.