my job blocks the site so i can't copy paste you the info, but if you go to
www.objector.org/
they have steps about how to start putting on record that you want conscientious objector status, in the event that selective service went into effect, so you would have a documented history to back up your claim.
"If you're male and a U.S. citizen, you're legally required to register with the Selective Service System, within thirty days before or twenty-nine days after your 18th birthday. "