Lol I have seen people apply right away on day one and get in... I think its blogs they don't like to disk out adsense accounts for unless they have traffic. If you have a social website which you have put some real work into they will probably let you in right away as they did me.But surely no ad netwrork would accept my website if theres no traffic to start off with? Shouldn't I wait?
*If it's clear your site has few members and posts the above may not work.