So, this might be a weird question, and, like so many, it might depend upon a particular dynasty, but "typically" how long can you be MIA before someone is likely to report you missing, or try to declare you dead? This is the same Imperium that can lose whole worlds, name several different worlds the same thing (I almost hope that some other "Cadia" got nuked; I'm actually rather sad/grumpy about that, favorite regiment, and all, but later), and forget several wars it is actively engaged in, or lose a whole division in the Warp, and 200 years later, declare them all traitors/deserters. It also depends on somewhat dodgy astrotelepathic communication, which can be spotty, disrupted, possibly even sabotaged. i know that a ship SHOULD need to pull into port,every so often, to stock up on supplies/crew refills, and this should ding in the dynasty's coffers, but what if you go missing for a while? How long should too long be, before your family starts trying to declare you dead, and pass your Warrant on to the next bearer?
At some point, in a story, I'm thinking of jumping eight, or so, years, and with some of the "HOLY CRAP!" events, already, it would seem weird, if not nice, to have eight straight years of "nothing much happened". Could get frozen competition, or lost in the warp, and come out eight years later; some ships come out a century late, or a decade before they left, so it doesn't seem hard.
As a last bit, as I am AFB, do either of the books, core, or Navis Primer, take into account maybe coming out way late, or actually before you left, or is that more fluff, and we know it happens, but the system would rather not mess with it, as it isn't common, by any stretch?