Adding a dependent

Hi all, apologies if this is a stupid question but what is the usual timeliness for a veteran adding a dependent? My husband sent in the request im December and was under the impression it was a quick process but nothing has happened yet, when I call the VA they just explain it is being processed and can't give me a time for how long that usually takes. He doesn't have access to any of the online tools as he is incarcerated so everything is being done via letter, not sure if that slows the process down. Thanks for your help!