An employer can issue it at any time, it's all done online then you get the copy printed out. It just depends when the employer wants to put the information in, print it out and post it. I work for a small business so I guess it's easier for our accountant to do it quickly than if we had 100 employees.
Another two weeks sounds a bit excessive. Ring them up every day, twice a day, and you'll get it within a week.