When do we get invites?

On most trackers it isn't mentioned how much we need to upload and how long we must wait to get invites.
Sometimes we must get to PU to be able to invite people, but is that always the case?

For example, when do we get invites on rSR? The site being in romanian it doesn't help :dabs:

yup.. @ rSR you also get invites only after you are promoted to PU

edit. and almost all trackers have this rules in their FAQ page..

Okay thanks. I still have to wait 2 weeks though..