what permission is required for "scheduled publishing"?

So we have a custom group with all rights (including replicate) to /content. Authors/editors can publish pages without any issue.

The problem is that when they want to use "scheduled publishing", they are not able to do it. Only admin can do this.

What permission is required for this feature? I looked at the permissions and I can only think of /etc/workflows? If this is the correct path, what permissions should I give?

Thank you.