Ads show up almost immediately...even if they aren't approved. They just won't show up on partner sites. If they are disapproved, they will give you warnings to fix them. Sometimes, they will flat out take them down. I have only had that happen once.
Are you sure that your quality/bid score is high enough to show up? What have you done to ensure that it's not just that you are being out-scored by others? What are your first page estimates?