If there are no concerns with your application then it takes a shorter amount of time than if something in your application warrants investigation. There are a lot of different factors that contribute to how long it takes, and in some situations it can take a while before they review your application. You just need a bit of patience.
However, if you do have concerns, give them a call. And once you do get an interview, make sure you're organised and have all your documentation in order. It makes it so much easier.
Good luck!