I'd say on average, it takes about 3-4 days before an interest check takes off and becomes a full-fledged RP. Though, it always helps when you're popular enough on the forums that people see your username and instantly just want to join.

RPers really have to look out for each other. We are a dying breed. If you don't help the newcomers, then how are we supposed to have the website grow? The only way to get others to notice is through bumping this up with posts.