There are several bg's, the wait time depends, it can be 5 minutes as it can be 10, usually average wait time is 7-8 tough.
That it being all day long, haven't noticed any perk time but i would guess that is around 17 up to 22.
Except for the fact of bg's being really unbalanced, it works very well and the bracket is quite populated.
If you need any more detail, just ask.