Take it at birth. Set it up over the next century. Everyone else could give it volantarily, and we could take finger prints in schools.
That might not work so well. I remember when it was mandatory to have your child immunized to enter school. Now you can sign a paper to not do so based on religion, medical, and personal reasons.
I'm sure anyone who wants to opt out would find a way. If it were even mandated to begin with.