This isn't exactly true. There is now a campaign offered to Newbies, so you could join one from day 1. It's the 777 campaign. Search for it in Service Discussions, the "Overview on Signature Campaigns" thread.

Remember to keep your posts constructive. Nothing's worse than perverting this benefit by posting meaningless posts just to keep your numbers high. Let's make sure we respect the entire community by only posting valuable, constructive comments.

Cheers.