On average, articles arrive within 3-5 days and books arrive within 8-10 days. These averages are for everyone, even full professors. A good rule of thumb: allow one week for articles and two weeks for books.
We try to borrow from libraries in our state and region (NC, VA, etc.) first, but if there isn't a copy, or if nearby copies are in use, we go on to try libraries farther away. It can take over two weeks for a book to come by library rate from Oregon, for example.