I strongly recommend creating an informal working group on the ABC concept (an initiative committee), as soon as possible. Invite in the group the market players who have a positive attitude towards the initiative. Make sure that they are representative of the market (you should have advertisers, media agencies and publishers), and that you get as many as possible key (big, influential) market players.
Write an initiative group membership application form, and send it to your full contact list. Please do not forget to attach it to a cover letter, in which you describe the goals etc., of the ABC initiative. Have copies of the applications with you at all times – you will need them when you meet people.