You left a small but important detail. The GI certs never expire. They may come in handy later in your career.

To answer to OP question. Back when I took them, they were all separate tests but from the same question bank. So, meaning you have to take the same test twice. Once for CFI and once for AGI. One you have the test results for the AGI, BGI or IGI in hand, all you have to do is go to the FSDO with a filled out 8710 and hand it over. Its a lot easier to get them now while you have those test in your head rather than to wait.