A Sapien can self assess if they are ready to have sex.

Adults, the way to check for this is do they exhibit the capacity and skill to handle emotional and physical needs of their own and the opposite sexual pole without needing to prioritize self over other or other over self.

Some sample tests - Do they know how to resolve conflicts without adult intervention until harmony is established?

Do they get up to pee the moment they feel the impulse inside?

Do they know how to say no without having a panic attack? (Strike this, it excludes coregulation as a biological predisposition of current Sapien population as is now)