Were original registrations done by mail? I see 5 domains registered on Aug. 5th, 1986, then no more domains for another month. And 12 on Dec. 11 1986, then again another month with no registrations.
EDIT: I operated a regional thing off BBN, and I could do the nasty bits of hoisting myself to administrative acceptance. I can't imagine what it must have required for someone just trying to 'join' before 1990-or-so.