Unlike today's mania over alternate covers and multiple print run cover variations, back when Peter David's "Supergirl" series began I don't believe there were too many instances of different cover art to designate another print run. I assume the same artwork was used on all editions of Issue #1 (the green shirt and skateboard cover), and you'll just have to carefully check the fine print to tell the difference.
Not altogether sure, but this MIGHT be the first printing:
http://supergirl.astraldream.net/covers/supergirl01.jpgYou might want to contact the webmistress and inquire further:
http://supergirl.astraldream.net/index.htmlhttp://supergirl.astraldream.net/author.htmlHope this helps.