At one point there was a simple way for admins to see if images were pending that no longer exists. I only discovered this when I went to add an item I'd just uploaded, which led me to discover 2-3 months worth in my groups.
A few days is normal. Even a week or more. But when it starts to get to be more than 4 weeks, there is a good chance you have an abandoned group. Then you report it to Abbie.