Usually, the longest period of waiting is waiting for your Police Information Check to return once you have applied for it! The form can sometimes be returned as early as 2 weeks but can take as long as 4 weeks, so apply early!
Once all of your documentation is submitted and if you are flexible with open availability, you usually can get started pretty fast! If you have limited availability or live far from where the families currently looking for support live, it can take more time.