This is indeed a very good idea, albeit difficult to implement. If I were a scammer who only wanted to cheat as many people as possible with my site, I could circumvent the rules quite easily. I'm founding the site, I'm not advertising it at all and therefore I won't have many players, if any.
After 6 months I come and say that my site has been around long enough to have a signature campaign.
This would not work; you maybe misunderstood my post or I wasn't clear enough
In your case, no matter how old your company is, you would have to open an official ANN in this forum first. I say "official", because a thread like "Hey, there is a new bookmaker, check it out" wouldn't qualify. It has to be a proper, not self-moderated thread, where you introduce your company to the community. In the next 6 months (it can be any timeframe) you would have to prove yourself. If all looks legit after these 6 months, you would be allowed to open a signature campaign.
So it would take 6 months of being nice until you are able to get more attention via campaign and could start scamming. This is probably too long for the average scammer, but not sure.